The ALL_CONS_COLUMNS view provides information about the columns specified in constraints placed on tables accessible by the current user.

ownerTEXTUser name of the constraint’s owner.
schema_nameTEXTName of the schema in which the constraint belongs.
constraint_nameTEXTName of the constraint.
table_nameTEXTName of the table to which the constraint belongs.
column_nameTEXTName of the column referenced in the constraint.
positionSMALLINTPosition of the column in the object definition.
constraint_defTEXTDefinition of the constraint.