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.

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SHOW CONSTRAINTS