<div id="docs-body">
 <div class="section">
  <div class="titlepage">
   <div>
    <div>
     <h4 class="title">
      <a name="gis-polygon-property-functions">
      </a>
      14.16.7.4 Polygon and MultiPolygon Property Functions
     </h4>
    </div>
   </div>
  </div>
  <p>
   Functions in this section return properties of
   <code class="literal">
    Polygon
   </code>
   or
   <code class="literal">
    MultiPolygon
   </code>
   values.
  </p>
  <p>
   Unless otherwise specified, functions in this section handle
        their geometry arguments as follows:
  </p>
  <div class="itemizedlist">
   <ul class="itemizedlist" style="list-style-type: disc; ">
    <li class="listitem">
     <p>
      If any argument is
      <code class="literal">
       NULL
      </code>
      or any geometry
            argument is an empty geometry, the return value is
      <code class="literal">
       NULL
      </code>
      .
     </p>
    </li>
    <li class="listitem">
     <p>
      If any geometry argument is not a syntactically well-formed
            geometry, an
      <a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_gis_invalid_data" target="_top">
       <code class="literal">
        ER_GIS_INVALID_DATA
       </code>
      </a>
      error
            occurs.
     </p>
    </li>
    <li class="listitem">
     <p>
      If any geometry argument is a syntactically well-formed
            geometry in an undefined spatial reference system (SRS), an
      <a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_srs_not_found" target="_top">
       <code class="literal">
        ER_SRS_NOT_FOUND
       </code>
      </a>
      error
            occurs.
     </p>
    </li>
    <li class="listitem">
     <p>
      For functions that take multiple geometry arguments, if
            those arguments are not in the same SRS, an
      <a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_gis_different_srids" target="_top">
       <code class="literal">
        ER_GIS_DIFFERENT_SRIDS
       </code>
      </a>
      error
            occurs.
     </p>
    </li>
    <li class="listitem">
     <p>
      Otherwise, the return value is non-
      <code class="literal">
       NULL
      </code>
      .
     </p>
    </li>
   </ul>
  </div>
  <p>
   These functions are available for obtaining polygon properties:
  </p>
  <div class="itemizedlist">
   <ul class="itemizedlist" style="list-style-type: disc; ">
    <li class="listitem">
     <a name="function_st-area">
     </a>
     <p>
      <a class="link" href="gis-polygon-property-functions.html#function_st-area">
       <code class="literal">
        ST_Area({
        <em class="replaceable">
         <code>
          poly
         </code>
        </em>
        |
        <em class="replaceable">
         <code>
          mpoly
         </code>
        </em>
        })
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045197144208">
     </a>
     <p>
      Returns a double-precision number indicating the area of the
      <code class="literal">
       Polygon
      </code>
      or
      <code class="literal">
       MultiPolygon
      </code>
      argument, as measured in its
            spatial reference system.
     </p>
     <p>
      <a class="link" href="gis-polygon-property-functions.html#function_st-area">
       <code class="literal">
        ST_Area()
       </code>
      </a>
      handles its
            arguments as described in the introduction to this section,
            with these exceptions:
     </p>
     <div class="itemizedlist">
      <ul class="itemizedlist" style="list-style-type: circle; ">
       <li class="listitem">
        <p>
         If the geometry is geometrically invalid, either the
                result is an undefined area (that is, it can be any
                number), or an error occurs.
        </p>
       </li>
       <li class="listitem">
        <p>
         If the geometry is valid but is not a
         <code class="literal">
          Polygon
         </code>
         or
         <code class="literal">
          MultiPolygon
         </code>
         object, an
         <a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_unexpected_geometry_type" target="_top">
          <code class="literal">
           ER_UNEXPECTED_GEOMETRY_TYPE
          </code>
         </a>
         error occurs.
        </p>
       </li>
       <li class="listitem">
        <p>
         If the geometry is a valid
         <code class="literal">
          Polygon
         </code>
         in
                a Cartesian SRS, the result is the Cartesian area of the
                polygon.
        </p>
       </li>
       <li class="listitem">
        <p>
         If the geometry is a valid
         <code class="literal">
          MultiPolygon
         </code>
         in a Cartesian SRS, the
                result is the sum of the Cartesian area of the polygons.
        </p>
       </li>
       <li class="listitem">
        <p>
         If the geometry is a valid
         <code class="literal">
          Polygon
         </code>
         in
                a geographic SRS, the result is the geodetic area of the
                polygon in that SRS, in square meters.
        </p>
       </li>
       <li class="listitem">
        <p>
         If the geometry is a valid
         <code class="literal">
          MultiPolygon
         </code>
         in a geographic SRS, the
                result is the sum of geodetic area of the polygons in
                that SRS, in square meters.
        </p>
       </li>
       <li class="listitem">
        <p>
         If an area computation results in
         <code class="literal">
          +inf
         </code>
         , an
         <a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_data_out_of_range" target="_top">
          <code class="literal">
           ER_DATA_OUT_OF_RANGE
          </code>
         </a>
         error occurs.
        </p>
       </li>
       <li class="listitem">
        <p>
         If the geometry has a geographic SRS with a longitude or
                latitude that is out of range, an error occurs:
        </p>
        <div class="itemizedlist">
         <ul class="itemizedlist" style="list-style-type: square; ">
          <li class="listitem">
           <p>
            If a longitude value is not in the range
                    (−180, 180], an
            <a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_geometry_param_longitude_out_of_range" target="_top">
             <code class="literal">
              ER_GEOMETRY_PARAM_LONGITUDE_OUT_OF_RANGE
             </code>
            </a>
            error occurs.
           </p>
          </li>
          <li class="listitem">
           <p>
            If a latitude value is not in the range [−90,
                    90], an
            <a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_geometry_param_latitude_out_of_range" target="_top">
             <code class="literal">
              ER_GEOMETRY_PARAM_LATITUDE_OUT_OF_RANGE
             </code>
            </a>
            error occurs.
           </p>
          </li>
         </ul>
        </div>
        <p>
         Ranges shown are in degrees. The exact range limits
                deviate slightly due to floating-point arithmetic.
        </p>
       </li>
      </ul>
     </div>
     <div class="copytoclipboard-wrapper">
      <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa91083537"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql&gt;</span> <span class="token keyword">SET</span> <span class="token variable">@poly</span> <span class="token operator">=</span>
       <span class="token string">'Polygon((0 0,0 3,3 0,0 0),(1 1,1 2,2 1,1 1))'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql&gt;</span> <span class="token keyword">SELECT</span> <span class="token function">ST_Area</span><span class="token punctuation">(</span><span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token variable">@poly</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ST_Area(ST_GeomFromText(@poly)) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span>                               4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>

<span class="token prompt">mysql&gt;</span> <span class="token keyword">SET</span> <span class="token variable">@mpoly</span> <span class="token operator">=</span>
       <span class="token string">'MultiPolygon(((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1)))'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql&gt;</span> <span class="token keyword">SELECT</span> <span class="token function">ST_Area</span><span class="token punctuation">(</span><span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token variable">@mpoly</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ST_Area(ST_GeomFromText(@mpoly)) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span>                                8 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
     </div>
    </li>
    <li class="listitem">
     <a name="function_st-centroid">
     </a>
     <p>
      <a class="link" href="gis-polygon-property-functions.html#function_st-centroid">
       <code class="literal">
        ST_Centroid({
        <em class="replaceable">
         <code>
          poly
         </code>
        </em>
        |
        <em class="replaceable">
         <code>
          mpoly
         </code>
        </em>
        })
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045197105808">
     </a>
     <p>
      Returns the mathematical centroid for the
      <code class="literal">
       Polygon
      </code>
      or
      <code class="literal">
       MultiPolygon
      </code>
      argument as a
      <code class="literal">
       Point
      </code>
      . The result is not guaranteed to be
            on the
      <code class="literal">
       MultiPolygon
      </code>
      .
     </p>
     <p>
      This function processes geometry collections by computing
            the centroid point for components of highest dimension in
            the collection. Such components are extracted and made into
            a single
      <code class="literal">
       MultiPolygon
      </code>
      ,
      <code class="literal">
       MultiLineString
      </code>
      , or
      <code class="literal">
       MultiPoint
      </code>
      for centroid computation.
     </p>
     <p>
      <a class="link" href="gis-polygon-property-functions.html#function_st-centroid">
       <code class="literal">
        ST_Centroid()
       </code>
      </a>
      handles its
            arguments as described in the introduction to this section,
            with these exceptions:
     </p>
     <div class="itemizedlist">
      <ul class="itemizedlist" style="list-style-type: circle; ">
       <li class="listitem">
        <p>
         The return value is
         <code class="literal">
          NULL
         </code>
         for the
                additional condition that the argument is an empty
                geometry collection.
        </p>
       </li>
       <li class="listitem">
        <p>
         If the geometry has an SRID value for a geographic
                spatial reference system (SRS), an
         <a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_not_implemented_for_geographic_srs" target="_top">
          <code class="literal">
           ER_NOT_IMPLEMENTED_FOR_GEOGRAPHIC_SRS
          </code>
         </a>
         error occurs.
        </p>
       </li>
      </ul>
     </div>
     <div class="copytoclipboard-wrapper">
      <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa95681294"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql&gt;</span> <span class="token keyword">SET</span> <span class="token variable">@poly</span> <span class="token operator">=</span>
       <span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token string">'POLYGON((0 0,10 0,10 10,0 10,0 0),(5 5,7 5,7 7,5 7,5 5))'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token prompt">mysql&gt;</span> <span class="token keyword">SELECT</span> <span class="token function">ST_GeometryType</span><span class="token punctuation">(</span><span class="token variable">@poly</span><span class="token punctuation">)</span><span class="token punctuation">,</span><span class="token function">ST_AsText</span><span class="token punctuation">(</span><span class="token function">ST_Centroid</span><span class="token punctuation">(</span><span class="token variable">@poly</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ST_GeometryType(@poly) <span class="token punctuation">|</span> ST_AsText(ST_Centroid(@poly))              <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> POLYGON                <span class="token punctuation">|</span> POINT(4.958333333333333 4.958333333333333) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
     </div>
    </li>
    <li class="listitem">
     <a name="function_st-exteriorring">
     </a>
     <p>
      <a class="link" href="gis-polygon-property-functions.html#function_st-exteriorring">
       <code class="literal">
        ST_ExteriorRing(
        <em class="replaceable">
         <code>
          poly
         </code>
        </em>
        )
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045197082512">
     </a>
     <p>
      Returns the exterior ring of the
      <code class="literal">
       Polygon
      </code>
      value
      <em class="replaceable">
       <code>
        poly
       </code>
      </em>
      as a
      <code class="literal">
       LineString
      </code>
      .
     </p>
     <p>
      <a class="link" href="gis-polygon-property-functions.html#function_st-exteriorring">
       <code class="literal">
        ST_ExteriorRing()
       </code>
      </a>
      handles its
            arguments as described in the introduction to this section.
     </p>
     <div class="copytoclipboard-wrapper">
      <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa72093698"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql&gt;</span> <span class="token keyword">SET</span> <span class="token variable">@poly</span> <span class="token operator">=</span>
       <span class="token string">'Polygon((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1))'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql&gt;</span> <span class="token keyword">SELECT</span> <span class="token function">ST_AsText</span><span class="token punctuation">(</span><span class="token function">ST_ExteriorRing</span><span class="token punctuation">(</span><span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token variable">@poly</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ST_AsText(ST_ExteriorRing(ST_GeomFromText(@poly))) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> LINESTRING(0 0,0 3,3 3,3 0,0 0)                    <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
     </div>
    </li>
    <li class="listitem">
     <a name="function_st-interiorringn">
     </a>
     <p>
      <a class="link" href="gis-polygon-property-functions.html#function_st-interiorringn">
       <code class="literal">
        ST_InteriorRingN(
        <em class="replaceable">
         <code>
          poly
         </code>
        </em>
        ,
        <em class="replaceable">
         <code>
          N
         </code>
        </em>
        )
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045197067584">
     </a>
     <p>
      Returns the
      <em class="replaceable">
       <code>
        N
       </code>
      </em>
      -th interior ring
            for the
      <code class="literal">
       Polygon
      </code>
      value
      <em class="replaceable">
       <code>
        poly
       </code>
      </em>
      as a
      <code class="literal">
       LineString
      </code>
      . Rings are numbered beginning
            with 1.
     </p>
     <p>
      <a class="link" href="gis-polygon-property-functions.html#function_st-interiorringn">
       <code class="literal">
        ST_InteriorRingN()
       </code>
      </a>
      handles
            its arguments as described in the introduction to this
            section.
     </p>
     <div class="copytoclipboard-wrapper">
      <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa96867082"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql&gt;</span> <span class="token keyword">SET</span> <span class="token variable">@poly</span> <span class="token operator">=</span>
       <span class="token string">'Polygon((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1))'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql&gt;</span> <span class="token keyword">SELECT</span> <span class="token function">ST_AsText</span><span class="token punctuation">(</span><span class="token function">ST_InteriorRingN</span><span class="token punctuation">(</span><span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token variable">@poly</span><span class="token punctuation">)</span><span class="token punctuation">,</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ST_AsText(ST_InteriorRingN(ST_GeomFromText(@poly),1)) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> LINESTRING(1 1,1 2,2 2,2 1,1 1)                       <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
     </div>
    </li>
    <li class="listitem">
     <a name="function_st-numinteriorrings">
     </a>
     <p>
      <a class="link" href="gis-polygon-property-functions.html#function_st-numinteriorrings">
       <code class="literal">
        ST_NumInteriorRing(
        <em class="replaceable">
         <code>
          poly
         </code>
        </em>
        )
       </code>
      </a>
      ,
      <a class="link" href="gis-polygon-property-functions.html#function_st-numinteriorrings">
       <code class="literal">
        ST_NumInteriorRings(
        <em class="replaceable">
         <code>
          poly
         </code>
        </em>
        )
       </code>
      </a>
     </p>
     <a class="indexterm" name="idm46045197050880">
     </a>
     <a class="indexterm" name="idm46045197049808">
     </a>
     <p>
      Returns the number of interior rings in the
      <code class="literal">
       Polygon
      </code>
      value
      <em class="replaceable">
       <code>
        poly
       </code>
      </em>
      .
     </p>
     <p>
      <a class="link" href="gis-polygon-property-functions.html#function_st-numinteriorrings">
       <code class="literal">
        ST_NumInteriorRing()
       </code>
      </a>
      and
      <a class="link" href="gis-polygon-property-functions.html#function_st-numinteriorrings">
       <code class="literal">
        ST_NuminteriorRings()
       </code>
      </a>
      handle their arguments as described in the introduction to
            this section.
     </p>
     <div class="copytoclipboard-wrapper">
      <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa12729138"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql&gt;</span> <span class="token keyword">SET</span> <span class="token variable">@poly</span> <span class="token operator">=</span>
       <span class="token string">'Polygon((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1))'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql&gt;</span> <span class="token keyword">SELECT</span> <span class="token function">ST_NumInteriorRings</span><span class="token punctuation">(</span><span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token variable">@poly</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ST_NumInteriorRings(ST_GeomFromText(@poly)) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span>                                           1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
     </div>
    </li>
   </ul>
  </div>
 </div>
 <br/>
</div>
