from emp e,(select deptno,avg(sal) avgsal from emp group by deptno) d
where e.deptno=d.deptno and e.sal>d.avgsal;
select * from table(dbms_xplan.display);
explain plan for
select empno,ename,sal,(select avg(sal) from emp where deptno=e.deptno) as avgsal from emp e where sal > (select avg(sal) from emp where deptno=e.deptno);
2015-09-19
不用糾結(jié)。我的也是一樣。相關(guān)子查詢比多表查詢占用了更多的CPU。
2019-11-15
你可以看看這個:http://www.iis7.com/b/plc/?1-9.html/?zjnb
希望能幫助到你
2019-05-23
每次查詢的時間跨度有點大,但我這普遍跟上面結(jié)論相反
2018-05-14
我也是
2017-04-12
我的也一樣
2016-08-20
我的也一樣,不必糾結(jié)
2015-12-27
我的也是 相關(guān)子查詢耗費了更多資源。?
2015-08-13
第一個是多表查詢多表查詢嵌套子查詢,第二個是相關(guān)子查詢
explain plan for
select e.empno,e.ename,e.sal,d.avgsal
from emp e,(select deptno,avg(sal) avgsal from emp group by deptno) d
where e.deptno=d.deptno and e.sal>d.avgsal;
select * from table(dbms_xplan.display);
explain plan for
select empno,ename,sal,(select avg(sal) from emp where deptno=e.deptno) as avgsal from emp e where sal > (select avg(sal) from emp where deptno=e.deptno);
select * from table(dbms_xplan.display);