ORACLE 資料庫查詢指定表的主鍵外鍵

Select b.table_name 主鍵表名,           b.column_name 主鍵列名,           a.table_name 外鍵表名,           a.column_name 外鍵列名From (Select a.constraint_name,                       b.table_name,                       b.column_name,                       a.r_constraint_name          From user_constraints a, user_cons_columns b         Where a.constraint_type = 'R'           And a.constraint_name = b.constraint_name) a,       (Select Distinct a.r_constraint_name, b.table_name, b.column_name          From user_constraints a, user_cons_columns b         Where a.constraint_type = 'R'           And a.r_constraint_name = b.constraint_name) bWhere a.r_constraint_name = b.r_constraint_name and b.table_name = 'HR_DUTY'