ld513508088的专栏

1、内连接 inner join 等价于 join INNER JOIN 关键字语法 SELECT column_name(s) FROM table_name1 INNER JOIN table_name2 ON table_name1.column_name=table_name2.column_name Persons" 表： Id_PLastNameFirstName

避免where和and直接相连

select * from tsys_opertor where password is null; 别死在 select * from tsys_opertor where password =‘’;

select后面跟的字段必须在group by 后面出现，聚集函数除外 问题：老师 我这么跟你说吧 我想查出来福建分公司 今年一月份的保单数据  不要重复的 答案：Select distinct i.mainindex,t.netname From imageindexnew i,TSYS_NET t where i.scandate>=to_date('2012-12-1 00:00:00