`information_schema.columns.udt_catalog`

mysql

type: SQL_IDENTIFIER NULL

Note:

Name of the database that the column data type (the underlying type of the domain, if applicable) is defined in (always the current database)

10-15

type: SQL_IDENTIFIER

Note:

Name of the database that the column data type (the underlying type of the domain, if applicable) is defined in (always the current database)

7.4-9.6

type: unknown

Note:

Name of the column data type's database (always the current database).