SQL - Check if a column auto increments

问题:

I am trying to run a query to check if a column auto increments. I can check type, default value, if it's nullable or not, etc. but I can't figure out how to test if it auto increments. Here is how I am testing for those other things:

SELECT *
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'my_table'
AND COLUMN_NAME = 'my_column'
AND DATA_TYPE = 'int'
AND COLUMN_DEFAULT IS NULL
AND IS_NULLABLE = 'NO'
--AND AUTO_INCREMENTS = 'YES'

Unfortunately there is no AUTO_INCREMENTS column to compare against. So how can I test if a column auto increments?

回答1:

For MySql, Check in the EXTRA column:

SELECT *
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'my_table'
    AND COLUMN_NAME = 'my_column'
    AND DATA_TYPE = 'int'
    AND COLUMN_DEFAULT IS NULL
    AND IS_NULLABLE = 'NO'
    AND EXTRA like '%auto_increment%'

For Sql Server, use sys.columns and the is_identity column:

SELECT 
    is_identity
FROM sys.columns
WHERE 
    object_id = object_id('my_table')
    AND name = 'my_column'

回答2:

Assuming MySQL, the EXTRA column will indicate whether it is AUTO_INCREMENT.

| TABLE_CATALOG | TABLE_SCHEMA | ... |          EXTRA | ... |
-------------------------------------------------------------
|           def |   db_2_00314 | ... | auto_increment | ... |

And for MSSQL, see here.

回答3:

Run: describe 'table_name'; In column EXTRA is what you looking for

回答4:

this works for sql server: select COLUMN_NAME, TABLE_NAME from INFORMATION_SCHEMA.COLUMNS where TABLE_SCHEMA = 'dbo' and COLUMNPROPERTY(object_id(TABLE_NAME), COLUMN_NAME, 'IsIdentity') = 1 order by TABLE_NAME