Primary keys

SELECT cra.conseq, a.attname
FROM _t_class t
INNER JOIN _t_attribute a ON t.oid = a.attrelid AND t.relname = ‘CUSTOMER’
INNER JOIN _t_constraint c ON t.oid = c.conrelid AND c.contype = ‘p’
INNER JOIN _t_const_relattr cra ON c.oid = cra.conid AND c.conrelid = a.attrelid AND cra.conattrnum = a.attnum
ORDER BY cra.conseq