Database Catalog Data
SHOW CONSTRAINTS
This view has a row for every constraint in every table in the database, except for NULL constraints. Those are presented as the column IS_NULLABLE at SHOW COLUMNS view.
The output is ordered by the table_name column.
Data can be filtered with IN TABLE table_name syntax.
The following table lists the output’s columns:
| Column name | Data type | Description |
|---|---|---|
| TABLE_NAME | VARCHAR(127) | The table name. This is the filter column. |
| COLUMN_NAME | VARCHAR(127) | The column the constraint is set on |
| CONSTRAINT_TYPE | CHAR(1) | r = foreign key constraint, p = primary key constraint, u = unique constraint |
| REF_TABLE_NAME | VARCHAR(127) | For foreign key constraint: The referenced table the foreign key is pointing to. Otherwise null. |
| REF_COL_NAME | VARCHAR(127) | For foreign key constraint: The column in the reference table the foreign key is referring to. Otherwise null. |