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 3.4 Getting Information About Databases and Tables
 ==================================================
 
 What if you forget the name of a database or table, or what the
 structure of a given table is (for example, what its columns are
 called)? MySQL addresses this problem through several statements that
 provide information about the databases and tables it supports.
 
 You have previously seen `SHOW DATABASES', which lists the databases
 managed by the server. To find out which database is currently
 selected, use the `DATABASE()' function:
 
      mysql> SELECT DATABASE();
      +------------+
      | DATABASE() |
      +------------+
      | menagerie  |
      +------------+
 
 If you have not yet selected any database, the result is `NULL'.
 
 To find out what tables the default database contains (for example,
 when you are not sure about the name of a table), use this command:
 
      mysql> SHOW TABLES;
      +---------------------+
      | Tables in menagerie |
      +---------------------+
      | event               |
      | pet                 |
      +---------------------+
 
 If you want to find out about the structure of a table, the `DESCRIBE'
 command is useful; it displays information about each of a table's
 columns:
 
      mysql> DESCRIBE pet;
      +---------+-------------+------+-----+---------+-------+
      | Field   | Type        | Null | Key | Default | Extra |
      +---------+-------------+------+-----+---------+-------+
      | name    | varchar(20) | YES  |     | NULL    |       |
      | owner   | varchar(20) | YES  |     | NULL    |       |
      | species | varchar(20) | YES  |     | NULL    |       |
      | sex     | char(1)     | YES  |     | NULL    |       |
      | birth   | date        | YES  |     | NULL    |       |
      | death   | date        | YES  |     | NULL    |       |
      +---------+-------------+------+-----+---------+-------+
 
 `Field' indicates the column name, `Type' is the data type for the
 column, `NULL' indicates whether the column can contain `NULL' values,
 `Key' indicates whether the column is indexed, and `Default' specifies
 the column's default value.
 
 If you have indexes on a table, `SHOW INDEX FROM TBL_NAME' produces
 information about them.
 

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