查看一个表对应的主键和外键的约束关系:
SELECT * FROM user_constraints t where t.table_name='HORDE'
查看关联HORDE的子表 :
select * from user_constraints where
R_CONSTRAINT_NAME in (select constraint_name from user_constraints where table_name = 'HORDE') ;
--在多行子查询中使用all操作符
select ename, sal, deptno from emp
where sal > all(select sal from emp where deptno = 30);
--等价于:
select ename, sal, deptno from emp where sal >
(select max(sal) from emp where deptno = 30);
--在多行子查询中使用any操作符
select ename, sal, deptno from emp
where sal > any(select sal from emp where deptno = 30);
--等价于
select ename, sal, deptno from emp where sal >
(select min(sal) from emp where deptno = 30);