标签：span com sel inf sql 关联 left join col src
普通关联查询
SELECT A1,B2 FROM A ,B WHERE A1=B1
子查询关联
SELECT A1,(SELECT B2 FROM B WHERE A1=B1) AS A2 ,A3, (SELECT B2 FROM B WHERE A3=B1)AS A4 FROM A
左连接left join
select A1,B.B2,A3,TB.B2 from A left join B on A.A1=B.B1 left join B TB on A.A3=TB.B1
标签：span com sel inf sql 关联 left join col src
原文地址：https://www.cnblogs.com/live8/p/10142107.html
