C#中mysql语句实现问题

Question

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 + "'";

Answer 1

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