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 seenSHOW DATABASES, which lists the databases managed by the server. To find out which database is currently selected, use theDATABASE() function:

mysql> SELECT DATABASE();+------------+| DATABASE() |+------------+| menagerie  |+------------+

If you have not yet selected any database, the result isNULL.

To find out what tables the default database contains (for example, when you are not sure about the name of a table), use this statement:

mysql> SHOW TABLES;+---------------------+| Tables_in_menagerie |+---------------------+| event               || pet                 |+---------------------+

The name of the column in the output produced by this statement is alwaysTables_in_db_name, wheredb_name is the name of the database. SeeSHOW TABLES Statement, for more information.

If you want to find out about the structure of a table, theDESCRIBE statement 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 containNULL values,Key indicates whether the column is indexed, andDefault specifies the column's default value.Extra displays special information about columns: If a column was created with theAUTO_INCREMENT option, the value isauto_increment rather than empty.

DESC is a short form ofDESCRIBE. SeeDESCRIBE Statement, for more information.

You can obtain theCREATE TABLE statement necessary to create an existing table using theSHOW CREATE TABLE statement. SeeSHOW CREATE TABLE Statement.

If you have indexes on a table,SHOW INDEX FROMtbl_name produces information about them. SeeSHOW INDEX Statement, for more about this statement.