DESCRIBE

Description

This statement is used to display the schema information of the specified table.

Syntax

DESC[RIBE] [db_name.]table_name [ALL];

Required Parameters

1.<table_name>

Specifies the table identifier (name), which must be unique within the database in which it is located.

Identifiers must begin with an alphabetic character (or any character in a language if unicode name support is enabled) and cannot contain spaces or special characters unless the entire identifier string is enclosed in backticks (e.g. My Object).

Identifiers cannot use reserved keywords.

For more details, see Identifier Requirements and Reserved Keywords.

Optional Parameters

1.<db_name>

Specifies the identifier (i.e., name) for the database.

Identifiers must begin with an alphabetic character (or any character in a given language if unicode name support is enabled) and cannot contain spaces or special characters unless the entire identifier string is enclosed in backticks (e.g., My Database).

Identifiers cannot use reserved keywords.

See Identifier Requirements and Reserved Keywords for more details.

2.RIBE

Returns description information of all columns in a table

3.ALL

Returns description information for all columns

Return Value

column name	description
IndexName	Table name
IndexKeysType	Table Model
Field	Column Name
Type	Data Types
Null	Whether NULL values are allowed
Key	Is it a key column
Default	Default Value
Extra	Display some additional information
Visible	Visible
DefineExpr	Defining Expressions
WhereClause	Filter Conditions Related Definitions

Access Control Requirements

Users executing this SQL command must have at least the following privileges:

Privilege	Object	Notes
SELECT_PRIV	Table	When executing DESC, you need to have the SELECT_PRIV privilege on the table being queried

Usage Notes

• If ALL is specified, the schema of all indexes (rollup) of the table is displayed.

Examples

1. Display the Base table schema

DESC test_table;

+---------+-------------+------+-------+---------+-------+
| Field   | Type        | Null | Key   | Default | Extra |
+---------+-------------+------+-------+---------+-------+
| user_id | bigint      | No   | true  | NULL    |       |
| name    | varchar(20) | Yes  | false | NULL    | NONE  |
| age     | int         | Yes  | false | NULL    | NONE  |
+---------+-------------+------+-------+---------+-------+

2. Display the schema of all indexes in the table

DESC demo.test_table ALL;

+------------+---------------+---------+-------------+--------------+------+-------+---------+-------+---------+------------+-------------+
| IndexName  | IndexKeysType | Field   | Type        | InternalType | Null | Key   | Default | Extra | Visible | DefineExpr | WhereClause |
+------------+---------------+---------+-------------+--------------+------+-------+---------+-------+---------+------------+-------------+
| test_table | DUP_KEYS      | user_id | bigint      | bigint       | No   | true  | NULL    |       | true    |            |             |
|            |               | name    | varchar(20) | varchar(20)  | Yes  | false | NULL    | NONE  | true    |            |             |
|            |               | age     | int         | int          | Yes  | false | NULL    | NONE  | true    |            |             |
+------------+---------------+---------+-------------+--------------+------+-------+---------+-------+---------+------------+-------------+