<div id="docs-body">
 <div class="section">
  <div class="titlepage">
   <div>
    <div>
     <h2 class="title">
      <a name="information-schema-introduction">
      </a>
      28.1 Introduction
     </h2>
    </div>
   </div>
  </div>
  <p>
   <code class="literal">
    INFORMATION_SCHEMA
   </code>
   provides access to database
   <span class="firstterm">
    metadata
   </span>
   , information about
      the MySQL server such as the name of a database or table, the data
      type of a column, or access privileges. Other terms that are
      sometimes used for this information are
   <span class="firstterm">
    data dictionary
   </span>
   and
   <span class="firstterm">
    system catalog
   </span>
   .
  </p>
  <div class="itemizedlist">
   <ul class="itemizedlist" style="list-style-type: disc; ">
    <li class="listitem">
     <p>
      <a class="xref" href="information-schema-introduction.html#information-schema-usage-notes" title="INFORMATION_SCHEMA Usage Notes">
       INFORMATION_SCHEMA Usage Notes
      </a>
     </p>
    </li>
    <li class="listitem">
     <p>
      <a class="xref" href="information-schema-introduction.html#information-schema-character-set-considerations" title="Character Set Considerations">
       Character Set Considerations
      </a>
     </p>
    </li>
    <li class="listitem">
     <p>
      <a class="xref" href="information-schema-introduction.html#information-schema-as-show-alternative" title="INFORMATION_SCHEMA as Alternative to SHOW Statements">
       INFORMATION_SCHEMA as Alternative to SHOW Statements
      </a>
     </p>
    </li>
    <li class="listitem">
     <p>
      <a class="xref" href="information-schema-introduction.html#information-schema-privileges" title="INFORMATION_SCHEMA and Privileges">
       INFORMATION_SCHEMA and Privileges
      </a>
     </p>
    </li>
    <li class="listitem">
     <p>
      <a class="xref" href="information-schema-introduction.html#information-schema-performance-considerations" title="Performance Considerations">
       Performance Considerations
      </a>
     </p>
    </li>
    <li class="listitem">
     <p>
      <a class="xref" href="information-schema-introduction.html#information-schema-standards-considerations" title="Standards Considerations">
       Standards Considerations
      </a>
     </p>
    </li>
    <li class="listitem">
     <p>
      <a class="xref" href="information-schema-introduction.html#information-schema-conventions" title="Conventions in the INFORMATION_SCHEMA Reference Sections">
       Conventions in the INFORMATION_SCHEMA Reference Sections
      </a>
     </p>
    </li>
    <li class="listitem">
     <p>
      <a class="xref" href="information-schema-introduction.html#information-schema-related-information" title="Related Information">
       Related Information
      </a>
     </p>
    </li>
   </ul>
  </div>
  <div class="simplesect">
   <div class="titlepage">
    <div>
     <div class="simple">
      <h3 class="title">
       <a name="information-schema-usage-notes">
       </a>
       INFORMATION_SCHEMA Usage Notes
      </h3>
     </div>
    </div>
   </div>
   <p>
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    is a database within each
        MySQL instance, the place that stores information about all the
        other databases that the MySQL server maintains. The
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    database contains several
        read-only tables. They are actually views, not base tables, so
        there are no files associated with them, and you cannot set
        triggers on them. Also, there is no database directory with that
        name.
   </p>
   <p>
    Although you can select
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    as
        the default database with a
    <a class="link" href="use.html" title="15.8.4 USE Statement">
     <code class="literal">
      USE
     </code>
    </a>
    statement, you can only read the contents of tables, not perform
    <a class="link" href="insert.html" title="15.2.7 INSERT Statement">
     <code class="literal">
      INSERT
     </code>
    </a>
    ,
    <a class="link" href="update.html" title="15.2.17 UPDATE Statement">
     <code class="literal">
      UPDATE
     </code>
    </a>
    , or
    <a class="link" href="delete.html" title="15.2.2 DELETE Statement">
     <code class="literal">
      DELETE
     </code>
    </a>
    operations on them.
   </p>
   <p>
    Here is an example of a statement that retrieves information
        from
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    :
   </p>
   <div class="copytoclipboard-wrapper">
    <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa89260799"><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">SELECT</span> <span class="token keyword">table_name</span><span class="token punctuation">,</span> table_type<span class="token punctuation">,</span> <span class="token keyword">engine</span>
       <span class="token keyword">FROM</span> information_schema<span class="token punctuation">.</span><span class="token keyword">tables</span>
       <span class="token keyword">WHERE</span> table_schema <span class="token operator">=</span> <span class="token string">'db5'</span>
       <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> <span class="token keyword">table_name</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> table_name <span class="token punctuation">|</span> table_type <span class="token punctuation">|</span> engine <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> fk         <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> InnoDB <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> fk2        <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> InnoDB <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> goto       <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> into       <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> k          <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> kurs       <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> loop       <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> pk         <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> InnoDB <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> t          <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> t2         <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> t3         <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> t7         <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> tables     <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> v          <span class="token punctuation">|</span> VIEW       <span class="token punctuation">|</span> NULL   <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> v2         <span class="token punctuation">|</span> VIEW       <span class="token punctuation">|</span> NULL   <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> v3         <span class="token punctuation">|</span> VIEW       <span class="token punctuation">|</span> NULL   <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> v56        <span class="token punctuation">|</span> VIEW       <span class="token punctuation">|</span> NULL   <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">17 rows in set (0.01 sec)</span></code></pre>
   </div>
   <p>
    Explanation: The statement requests a list of all the tables in
        database
    <code class="literal">
     db5
    </code>
    , showing just three pieces of
        information: the name of the table, its type, and its storage
        engine.
   </p>
   <p>
    Information about generated invisible primary keys is visible by
        default in all
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    tables
        describing table columns, keys, or both, such as the
    <a class="link" href="information-schema-columns-table.html" title="28.3.8 The INFORMATION_SCHEMA COLUMNS Table">
     <code class="literal">
      COLUMNS
     </code>
    </a>
    and
    <a class="link" href="information-schema-statistics-table.html" title="28.3.34 The INFORMATION_SCHEMA STATISTICS Table">
     <code class="literal">
      STATISTICS
     </code>
    </a>
    tables. If you wish to
        make such information hidden from queries that select from these
        tables, you can do so by setting the value of the
    <a class="link" href="server-system-variables.html#sysvar_show_gipk_in_create_table_and_information_schema">
     <code class="literal">
      show_gipk_in_create_table_and_information_schema
     </code>
    </a>
    server system variable to
    <code class="literal">
     OFF
    </code>
    . For more
        information, see
    <a class="xref" href="create-table-gipks.html" title="15.1.20.11 Generated Invisible Primary Keys">
     Section 15.1.20.11, “Generated Invisible Primary Keys”
    </a>
    .
   </p>
  </div>
  <div class="simplesect">
   <div class="titlepage">
    <div>
     <div class="simple">
      <h3 class="title">
       <a name="information-schema-character-set-considerations">
       </a>
       Character Set Considerations
      </h3>
     </div>
    </div>
   </div>
   <p>
    The definition for character columns (for example,
    <code class="literal">
     TABLES.TABLE_NAME
    </code>
    ) is generally
    <code class="literal">
     VARCHAR(
     <em class="replaceable">
      <code>
       N
      </code>
     </em>
     ) CHARACTER SET
        utf8mb3
    </code>
    where
    <em class="replaceable">
     <code>
      N
     </code>
    </em>
    is at least
        64. MySQL uses the default collation for this character set
        (
    <code class="literal">
     utf8mb3_general_ci
    </code>
    ) for all searches, sorts,
        comparisons, and other string operations on such columns.
   </p>
   <p>
    Because some MySQL objects are represented as files, searches in
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    string columns can be
        affected by file system case sensitivity. For more information,
        see
    <a class="xref" href="charset-collation-information-schema.html" title="12.8.7 Using Collation in INFORMATION_SCHEMA Searches">
     Section 12.8.7, “Using Collation in INFORMATION_SCHEMA Searches”
    </a>
    .
   </p>
  </div>
  <div class="simplesect">
   <div class="titlepage">
    <div>
     <div class="simple">
      <h3 class="title">
       <a name="information-schema-as-show-alternative">
       </a>
       INFORMATION_SCHEMA as Alternative to SHOW Statements
      </h3>
     </div>
    </div>
   </div>
   <p>
    The
    <code class="literal">
     SELECT ... FROM INFORMATION_SCHEMA
    </code>
    statement is intended as a more consistent way to provide access
        to the information provided by the various
    <a class="link" href="show.html" title="15.7.7 SHOW Statements">
     <code class="literal">
      SHOW
     </code>
    </a>
    statements that MySQL
        supports (
    <a class="link" href="show-databases.html" title="15.7.7.15 SHOW DATABASES Statement">
     <code class="literal">
      SHOW DATABASES
     </code>
    </a>
    ,
    <a class="link" href="show-tables.html" title="15.7.7.39 SHOW TABLES Statement">
     <code class="literal">
      SHOW TABLES
     </code>
    </a>
    , and so forth). Using
    <a class="link" href="select.html" title="15.2.13 SELECT Statement">
     <code class="literal">
      SELECT
     </code>
    </a>
    has these advantages,
        compared to
    <a class="link" href="show.html" title="15.7.7 SHOW Statements">
     <code class="literal">
      SHOW
     </code>
    </a>
    :
   </p>
   <div class="itemizedlist">
    <ul class="itemizedlist" style="list-style-type: disc; ">
     <li class="listitem">
      <p>
       It conforms to Codd's rules, because all access is done on
            tables.
      </p>
     </li>
     <li class="listitem">
      <p>
       You can use the familiar syntax of the
       <a class="link" href="select.html" title="15.2.13 SELECT Statement">
        <code class="literal">
         SELECT
        </code>
       </a>
       statement, and only
            need to learn some table and column names.
      </p>
     </li>
     <li class="listitem">
      <p>
       The implementor need not worry about adding keywords.
      </p>
     </li>
     <li class="listitem">
      <p>
       You can filter, sort, concatenate, and transform the results
            from
       <code class="literal">
        INFORMATION_SCHEMA
       </code>
       queries into
            whatever format your application needs, such as a data
            structure or a text representation to parse.
      </p>
     </li>
     <li class="listitem">
      <p>
       This technique is more interoperable with other database
            systems. For example, Oracle Database users are familiar
            with querying tables in the Oracle data dictionary.
      </p>
     </li>
    </ul>
   </div>
   <p>
    Because
    <a class="link" href="show.html" title="15.7.7 SHOW Statements">
     <code class="literal">
      SHOW
     </code>
    </a>
    is familiar and
        widely used, the
    <a class="link" href="show.html" title="15.7.7 SHOW Statements">
     <code class="literal">
      SHOW
     </code>
    </a>
    statements
        remain as an alternative. In fact, along with the implementation
        of
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    , there are enhancements
        to
    <a class="link" href="show.html" title="15.7.7 SHOW Statements">
     <code class="literal">
      SHOW
     </code>
    </a>
    as described in
    <a class="xref" href="extended-show.html" title="28.8 Extensions to SHOW Statements">
     Section 28.8, “Extensions to SHOW Statements”
    </a>
    .
   </p>
  </div>
  <div class="simplesect">
   <div class="titlepage">
    <div>
     <div class="simple">
      <h3 class="title">
       <a name="information-schema-privileges">
       </a>
       INFORMATION_SCHEMA and Privileges
      </h3>
     </div>
    </div>
   </div>
   <p>
    For most
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    tables, each
        MySQL user has the right to access them, but can see only the
        rows in the tables that correspond to objects for which the user
        has the proper access privileges. In some cases (for example,
        the
    <code class="literal">
     ROUTINE_DEFINITION
    </code>
    column in the
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    <a class="link" href="information-schema-routines-table.html" title="28.3.30 The INFORMATION_SCHEMA ROUTINES Table">
     <code class="literal">
      ROUTINES
     </code>
    </a>
    table), users who have
        insufficient privileges see
    <code class="literal">
     NULL
    </code>
    . Some tables
        have different privilege requirements; for these, the
        requirements are mentioned in the applicable table descriptions.
        For example,
    <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine">
     <code class="literal">
      InnoDB
     </code>
    </a>
    tables (tables
        with names that begin with
    <code class="literal">
     INNODB_
    </code>
    ) require
        the
    <a class="link" href="privileges-provided.html#priv_process">
     <code class="literal">
      PROCESS
     </code>
    </a>
    privilege.
   </p>
   <p>
    The same privileges apply to selecting information from
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    and viewing the same
        information through
    <a class="link" href="show.html" title="15.7.7 SHOW Statements">
     <code class="literal">
      SHOW
     </code>
    </a>
    statements. In either case, you must have some privilege on an
        object to see information about it.
   </p>
  </div>
  <div class="simplesect">
   <div class="titlepage">
    <div>
     <div class="simple">
      <h3 class="title">
       <a name="information-schema-performance-considerations">
       </a>
       Performance Considerations
      </h3>
     </div>
    </div>
   </div>
   <p>
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    queries that search for
        information from more than one database might take a long time
        and impact performance. To check the efficiency of a query, you
        can use
    <a class="link" href="explain.html" title="15.8.2 EXPLAIN Statement">
     <code class="literal">
      EXPLAIN
     </code>
    </a>
    . For information
        about using
    <a class="link" href="explain.html" title="15.8.2 EXPLAIN Statement">
     <code class="literal">
      EXPLAIN
     </code>
    </a>
    output to
        tune
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    queries, see
    <a class="xref" href="information-schema-optimization.html" title="10.2.3 Optimizing INFORMATION_SCHEMA Queries">
     Section 10.2.3, “Optimizing INFORMATION_SCHEMA Queries”
    </a>
    .
   </p>
  </div>
  <div class="simplesect">
   <div class="titlepage">
    <div>
     <div class="simple">
      <h3 class="title">
       <a name="information-schema-standards-considerations">
       </a>
       Standards Considerations
      </h3>
     </div>
    </div>
   </div>
   <p>
    The implementation for the
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    table structures in MySQL follows the ANSI/ISO SQL:2003 standard
        Part 11
    <em class="citetitle">
     Schemata
    </em>
    . Our intent is
        approximate compliance with SQL:2003 core feature F021
    <em class="citetitle">
     Basic information schema
    </em>
    .
   </p>
   <p>
    Users of SQL Server 2000 (which also follows the standard) may
        notice a strong similarity. However, MySQL has omitted many
        columns that are not relevant for our implementation, and added
        columns that are MySQL-specific. One such added column is the
    <code class="literal">
     ENGINE
    </code>
    column in the
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    <a class="link" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table">
     <code class="literal">
      TABLES
     </code>
    </a>
    table.
   </p>
   <p>
    Although other DBMSs use a variety of names, like
    <code class="literal">
     syscat
    </code>
    or
    <code class="literal">
     system
    </code>
    , the
        standard name is
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    .
   </p>
   <p>
    To avoid using any name that is reserved in the standard or in
        DB2, SQL Server, or Oracle, we changed the names of some columns
        marked
    <span class="quote">
     “
     <span class="quote">
      MySQL extension
     </span>
     ”
    </span>
    . (For example, we changed
    <code class="literal">
     COLLATION
    </code>
    to
    <code class="literal">
     TABLE_COLLATION
    </code>
    in the
    <a class="link" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table">
     <code class="literal">
      TABLES
     </code>
    </a>
    table.) See the list of
        reserved words near the end of this article:
    <a class="ulink" href="https://web.archive.org/web/20070428032454/http://www.dbazine.com/db2/db2-disarticles/gulutzan5" target="_blank">
     https://web.archive.org/web/20070428032454/http://www.dbazine.com/db2/db2-disarticles/gulutzan5
    </a>
    .
   </p>
  </div>
  <div class="simplesect">
   <div class="titlepage">
    <div>
     <div class="simple">
      <h3 class="title">
       <a name="information-schema-conventions">
       </a>
       Conventions in the INFORMATION_SCHEMA Reference Sections
      </h3>
     </div>
    </div>
   </div>
   <p>
    The following sections describe each of the tables and columns
        in
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    . For each column, there
        are three pieces of information:
   </p>
   <div class="itemizedlist">
    <ul class="itemizedlist" style="list-style-type: disc; ">
     <li class="listitem">
      <p>
       <span class="quote">
        “
        <span class="quote">
         <code class="literal">
          INFORMATION_SCHEMA
         </code>
         Name
        </span>
        ”
       </span>
       indicates the name for the column in the
       <code class="literal">
        INFORMATION_SCHEMA
       </code>
       table. This
            corresponds to the standard SQL name unless the
       <span class="quote">
        “
        <span class="quote">
         Remarks
        </span>
        ”
       </span>
       field says
       <span class="quote">
        “
        <span class="quote">
         MySQL
            extension.
        </span>
        ”
       </span>
      </p>
     </li>
     <li class="listitem">
      <p>
       <span class="quote">
        “
        <span class="quote">
         <a class="link" href="show.html" title="15.7.7 SHOW Statements">
          <code class="literal">
           SHOW
          </code>
         </a>
         Name
        </span>
        ”
       </span>
       indicates the equivalent field name in the closest
       <a class="link" href="show.html" title="15.7.7 SHOW Statements">
        <code class="literal">
         SHOW
        </code>
       </a>
       statement, if there is
            one.
      </p>
     </li>
     <li class="listitem">
      <p>
       <span class="quote">
        “
        <span class="quote">
         Remarks
        </span>
        ”
       </span>
       provides additional information where
            applicable. If this field is
       <code class="literal">
        NULL
       </code>
       , it
            means that the value of the column is always
       <code class="literal">
        NULL
       </code>
       . If this field says
       <span class="quote">
        “
        <span class="quote">
         MySQL
            extension,
        </span>
        ”
       </span>
       the column is a MySQL extension to
            standard SQL.
      </p>
     </li>
    </ul>
   </div>
   <p>
    Many sections indicate what
    <a class="link" href="show.html" title="15.7.7 SHOW Statements">
     <code class="literal">
      SHOW
     </code>
    </a>
    statement is equivalent to a
    <a class="link" href="select.html" title="15.2.13 SELECT Statement">
     <code class="literal">
      SELECT
     </code>
    </a>
    that retrieves information
        from
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    . For
    <a class="link" href="show.html" title="15.7.7 SHOW Statements">
     <code class="literal">
      SHOW
     </code>
    </a>
    statements that display
        information for the default database if you omit a
    <code class="literal">
     FROM
     <em class="replaceable">
      <code>
       db_name
      </code>
     </em>
    </code>
    clause, you can
        often select information for the default database by adding an
    <code class="literal">
     AND TABLE_SCHEMA = SCHEMA()
    </code>
    condition to the
    <code class="literal">
     WHERE
    </code>
    clause of a query that retrieves
        information from an
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    table.
   </p>
  </div>
  <div class="simplesect">
   <div class="titlepage">
    <div>
     <div class="simple">
      <h3 class="title">
       <a name="information-schema-related-information">
       </a>
       Related Information
      </h3>
     </div>
    </div>
   </div>
   <p>
    These sections discuss additional
    <code class="literal">
     INFORMATION_SCHEMA
    </code>
    -related topics:
   </p>
   <div class="itemizedlist">
    <ul class="itemizedlist" style="list-style-type: disc; ">
     <li class="listitem">
      <p>
       information about
       <code class="literal">
        INFORMATION_SCHEMA
       </code>
       tables specific to the
       <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine">
        <code class="literal">
         InnoDB
        </code>
       </a>
       storage engine:
       <a class="xref" href="innodb-information-schema-tables.html" title="28.4 INFORMATION_SCHEMA InnoDB Tables">
        Section 28.4, “INFORMATION_SCHEMA InnoDB Tables”
       </a>
      </p>
     </li>
     <li class="listitem">
      <p>
       information about
       <code class="literal">
        INFORMATION_SCHEMA
       </code>
       tables specific to the thread pool plugin:
       <a class="xref" href="thread-pool-information-schema-tables.html" title="28.5 INFORMATION_SCHEMA Thread Pool Tables">
        Section 28.5, “INFORMATION_SCHEMA Thread Pool Tables”
       </a>
      </p>
     </li>
     <li class="listitem">
      <p>
       information about
       <code class="literal">
        INFORMATION_SCHEMA
       </code>
       tables specific to the
       <code class="literal">
        CONNECTION_CONTROL
       </code>
       plugin:
       <a class="xref" href="connection-control-information-schema-tables.html" title="28.6 INFORMATION_SCHEMA Connection-Control Tables">
        Section 28.6, “INFORMATION_SCHEMA Connection-Control Tables”
       </a>
      </p>
     </li>
     <li class="listitem">
      <p>
       Answers to questions that are often asked concerning the
       <code class="literal">
        INFORMATION_SCHEMA
       </code>
       database:
       <a class="xref" href="faqs-information-schema.html" title="A.7 MySQL 8.4 FAQ: INFORMATION_SCHEMA">
        Section A.7, “MySQL 8.4 FAQ: INFORMATION_SCHEMA”
       </a>
      </p>
     </li>
     <li class="listitem">
      <p>
       <code class="literal">
        INFORMATION_SCHEMA
       </code>
       queries and the
            optimizer:
       <a class="xref" href="information-schema-optimization.html" title="10.2.3 Optimizing INFORMATION_SCHEMA Queries">
        Section 10.2.3, “Optimizing INFORMATION_SCHEMA Queries”
       </a>
      </p>
     </li>
     <li class="listitem">
      <p>
       The effect of collation on
       <code class="literal">
        INFORMATION_SCHEMA
       </code>
       comparisons:
       <a class="xref" href="charset-collation-information-schema.html" title="12.8.7 Using Collation in INFORMATION_SCHEMA Searches">
        Section 12.8.7, “Using Collation in INFORMATION_SCHEMA Searches”
       </a>
      </p>
     </li>
    </ul>
   </div>
  </div>
 </div>
 <br/>
</div>
