The SYS_KEY_COLUMN_USAGE table contains information to match columns with constraints. It has the following columns:

Column Name	Data Type	Description
CONSTRAINT_CATALOG	VARCHAR(128)	The Google Cloud project that contains the constraint.
CONSTRAINT_SCHEMA	VARCHAR(128)	The dataset that contains the constraint.
CONSTRAINT_NAME	VARCHAR(128)	The name of the constraint.
TABLE_CATALOG	VARCHAR(128)	The Google Cloud project that contains the table.
TABLE_SCHEMA	VARCHAR(128)	The dataset that contains the table.
TABLE_NAME	VARCHAR(128)	The name of the table which the column belongs to.
COLUMN_NAME	VARCHAR(128)	The name of the column.
ORDINAL_POSITION	INT	The position of the column in the key.