# 37.32. key_column_usage
The view key_column_usage
identifies all columns in the current database that are restricted by some unique, primary key, or foreign key constraint. Check constraints are not included in this view. Only those columns are shown that the current user has access to, by way of being the owner or having some privilege.
Table 37.30. key_column_usage
Columns
Column Type Description |
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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 that contains the column that is restricted by this constraint (always the current database) |
table_schema sql_identifier Name of the schema that contains the table that contains the column that is restricted by this constraint |
table_name sql_identifier Name of the table that contains the column that is restricted by this constraint |
column_name sql_identifier Name of the column that is restricted by this constraint |
ordinal_position cardinal_number Ordinal position of the column within the constraint key (count starts at 1) |
position_in_unique_constraint cardinal_number For a foreign-key constraint, ordinal position of the referenced column within its unique constraint (count starts at 1); otherwise null |