1. IN 查询效率低下,可以使用联表查询来优化效率,如下SQL 优化,将性能提升了10倍。
1.优化前:
update tag set washTimes=washTimes+1 where tag.TagNo in (select mx.tagno from BusinessEventMX mx where mx.eventID=1)
and tag.ID in (select TAGID from asset where asset.ORGID = 2);
2.优化后的SQL
update tag, asset,`businesseventmx` mx set tag.`WashTimes` =`tag` .`WashTimes` +1
where `asset`.`ORGID` =2 and tag.`TagNo` =mx.`TagNo` and tag.`ID` =`asset`.`TagID` ;