The view table_constraints contains all constraints belonging to tables that the current user owns or has some privilege other than SELECT on.
Table 34-48. table_constraints Columns
|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|
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