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三表关联 lEFt join

3张表或几张表的写法都是一样的 如select * from a left join b on a.col1 = b.col1 left join c on a.col1 = c.col1 where ...

SELECT * FROM tb_brand c left join (SELECT * FROM tb_product a,tb_info b WHERE a.itemname = b.itemname AND a.catname ='手机') d on d.brand = c.brand; 没试,但写完后感觉只会比你的更慢。 我认为,想提速最好不要三表联查,让前两个表...

大哥你以B为主表查埃。以A去LEFT JOIN肯定会多的! select b.sheetid,b.productid,c.name,b.number,a.companyid,a.ordertimefrom orderitem b left join order a on b.sheetid = a.sheetid left join product c on b.productid = c.productid

MSSQL请参考: Upate [表B] Set [金额]=c.[金额] From [表B] b Left Join [表A] a on a.[产品ID]=b.[产品ID] Left Join [表C] c on c.[资金池ID]=a.[资金池ID] 欢迎追问。

首先,你得确认,3个表中哪个表需要显示全部数据(假设为shop)。然后,用左关联始终把shop放前面连接就可以了。比如: select a.*,b.Fitemname as username,c.Fitemname as Typename from shop a left outer join user b on a.FuserID=b.Fitemid...

可以写两个join $result = $room->join('left join r_hospital on r_department.hospital_id=r_hospital.id ')->join(' doctor on doctor.id = xx.id')->where($condition)->select();

比如有三张表,student,teacher , project : 第一种方法:select * from student,teacher,project where student.id=teacher.sid and student.id=project.sid; 第二种:select * from student inner join teacher on student.id=teacher.sid i...

inner join(等值连接) 只返回两个表中联结字段相等的行 left join(左联接) 返回包括左表中的所有记录和右表中联结字段相等的记录 right join(右联接) 返回包括右表中的所有记录和左表中联结字段相等的记录 INNER JOIN 语法: INNER JOIN 连接两...

select * from A left join B on (A.id = B.uid) left join C on (A.id = C.tid) group by A.kk

select t_cp.id, t_cp.proc, t_odid_cpid.num from t_odid_cpid left join t_cp on t_cp.id = t_odid_cpid.cpid left join T_ORDER on t_odid_cpid.odid = T_ORDER.odid Where T_ORDER.B_zzdm = '785390650'SQL语句尽量不要用子查询,子查询速度...

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