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
- 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 |
+---------+-------------+------+-------+---------+-------+
- 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 | | |
+------------+---------------+---------+-------------+--------------+------+-------+---------+-------+---------+------------+-------------+
