`information_schema.key_column_usage.column_name`

mysql

type: VARCHAR NULL

type: VARCHAR NOT NULL

5.7

type: NULL

Note:

Column name of the constraint.

5.1-10.8

type: VARCHAR NOT NULL

Note:

Column name of the constraint.

type: VARCHAR(64) NOT NULL

Note:

The name of the column with constraints.

4-6.1

type: SQL_IDENTIFIER NULL

Note:

Name of the column that is restricted by this constraint

10-15

type: SQL_IDENTIFIER

Note:

Name of the column that is restricted by this constraint

8.2-9.6

Note:

Name of the column that is restricted by some constraint

7.4-8.1

type: unknown

Note:

Name of the constrained column.

1-21.2

type: NVARCHAR(128) NULL

Note:

Column name.