- C#中mysql语句实现问题
-
想把下面两条语句合成一条，实现的是查询接单人（未接单时为空）电话和订单信息的功能，第一条是有接单人，第二条没有，该怎么合并呢？谢谢大家！
1.mycmd.CommandText = @"select recordID,state,deadLine,revent,phone from
records,users where
records.serverID is not null and records.serverID=users.stuID and
records.userID='" + ShareClass.ID + "')";
2.mycmd.CommandText = @"select recordID,state,deadLine,revent from
records where
records.serverID is null and records.userID='" + ShareClass.ID + "'";
已经找到合适的写法了：
select recordID,state,deadLine,revent,phone from
records left join users on records.serverID=users.stuID where
records.userID=''
谢谢大家
能实现的话也可以，但是 如果用
3.@"select recordID,state,deadLine,revent,**phone from
records,users** where
records.serverID is null and records.userID='" + ShareClass.ID + "'";
就会出现records表中查到的记录与users表中的所有phone组合，却不是phone显示为空
select recordID,state,deadLine,revent,phone from
records,users where
records.serverID is not null and records.serverID=users.stuID and
records.userID=''
UNION
select recordID,state,deadLine,revent ,phone as null from
records，users where
records.serverID is null and records.userID=''
这样可以不，你试试
