2019-02-25
閱讀量:
739
SQL語句的效率有區(qū)別嗎
問題描述:
這兩個SQL的效率有區(qū)別嗎?
select * from A
left join B on A.aid=B.aid
where A.aid=100;
select * from (
select * from A where A.aid=100
) AA
left join B on AA.aid=B.aid;
怎么看SQL執(zhí)行解釋分析呢?
解決方法:
EXPLAIN select * from A
left join B on A.aid=B.aid
where A.aid=100;
EXPLAIN select * from (
select * from A where A.aid=100
) AA
left join B on AA.aid=B.aid;






評論(0)


暫無數(shù)據(jù)
推薦帖子
0條評論
0條評論
0條評論
1條評論