加入 3 个或更多 table 并对字段求和

Question

我想加入 3 tables.

结果是其中一个字段 - 来自另一个字段的 SUM table 喜欢这张图片，请帮助

Answer 1

您无需加入 tblwork，因为您可以从其他 2 个表中获取所有必填字段。

以下查询应该有效：

select t1.nmstudent,
           sum(case when t2.idwork = 'w001' then t2.trprice else 0 end) as w001,
           sum(case when t2.idwork = 'w002' then t2.trprice else 0 end) as w002,
           sum(case when t2.idwork = 'w003' then t2.trprice else 0 end) as w003,
           sum(case when t2.idwork = 'w004' then t2.trprice else 0 end) as w004
    from tblstudent t1
    inner join tblTrans t2
    on t1.idstudent = t2.idstudent
    group by t1.idstudent;

希望对您有所帮助！

加入 3 个或更多 table 并对字段求和

joining 3 or more table and sum the fields

mysql

sql

firebird