PostgreSQL

constraint_catalog sql_identifier

Name of the database that contains the constraint (always the current database)

constraint_schema sql_identifier

Name of the schema that contains the constraint

constraint_name sql_identifier

Name of the constraint

table_catalog sql_identifier

Name of the database that contains the table (always the current database)

table_schema sql_identifier

Name of the schema that contains the table

table_name sql_identifier

Name of the table

constraint_type character_data

Type of the constraint: CHECK, FOREIGN KEY, PRIMARY KEY, or UNIQUE

is_deferrable yes_or_no

YES if the constraint is deferrable, NO if not

initially_deferred yes_or_no

YES if the constraint is deferrable and initially deferred, NO if not

enforced yes_or_no

Applies to a feature not available in PostgreSQL (currently always YES)

nulls_distinct yes_or_no

If the constraint is a unique constraint, then YES if the constraint treats nulls as distinct or NO if it treats nulls as not distinct, otherwise null for other types of constraints.