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     <h3 class="title">
      <a name="null-values">
      </a>
      11.1.7 NULL Values
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  <p>
   The
   <code class="literal">
    NULL
   </code>
   value means
   <span class="quote">
    “
    <span class="quote">
     no data.
    </span>
    ”
   </span>
   <code class="literal">
    NULL
   </code>
   can be written in any lettercase.
  </p>
  <p>
   Be aware that the
   <code class="literal">
    NULL
   </code>
   value is different
        from values such as
   <code class="literal">
    0
   </code>
   for numeric types or
        the empty string for string types. For more information, see
   <a class="xref" href="problems-with-null.html" title="B.3.4.3 Problems with NULL Values">
    Section B.3.4.3, “Problems with NULL Values”
   </a>
   .
  </p>
  <p>
   For text file import or export operations performed with
   <a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement">
    <code class="literal">
     LOAD DATA
    </code>
   </a>
   or
   <a class="link" href="select-into.html" title="15.2.13.1 SELECT ... INTO Statement">
    <code class="literal">
     SELECT ... INTO
        OUTFILE
    </code>
   </a>
   ,
   <code class="literal">
    NULL
   </code>
   is represented by the
   <code class="literal">
    \N
   </code>
   sequence. See
   <a class="xref" href="load-data.html" title="15.2.9 LOAD DATA Statement">
    Section 15.2.9, “LOAD DATA Statement”
   </a>
   .
  </p>
  <p>
   For sorting with
   <code class="literal">
    ORDER BY
   </code>
   ,
   <code class="literal">
    NULL
   </code>
   values sort before other values for
        ascending sorts, after other values for descending sorts.
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