正文关于SQL语言,查询关联多张表出现的,无法返回空值的问题。IP云V管理员/2022-09-14/0 阅读 09/14小程序:扫一扫查出行【扫一扫了解最新限行尾号】复制小程序 用外连接:SELECT * from PERempms left outer join PERPROMSon PERPROMS.BRANCH =PERempms.BRANCHleft outer join PEREDUMSon PEREDUMS.Education_CODE =PERempms.Educationleft outer join PERGRDMS on PERGRDMS.GRADE=PEREMPMS.GRADE