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orAClE三表联合查询

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...

select A.姓名,A.性别,D.选课内容 from Aleft join (SELECT B.学号 student, wmsys.wm_concat (C.课程名称) as 选课内容 FROM Bleft join C on B.课程id = C.课程IDGROUP BY B.学号) as D on A.学号 = D.学号

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

select A.*,B.*,C.* from TB_EC_ACT_ORD A,TB_EC_ORD_EQPT B,TB_PM_EQPT C where A.SEQ_ID = B.SEQ_ID and B.EQPT_ID=C.EQPT_ID;

以oracle使用rownum伪列实现分页为例: 三表连接分页示例代码如下: select * from (select rownum r,k.kch,k.kcm,cj.cj,x.xh,x.xm from KCB k,CJB cj,XSB x where k.kch = cj.kch and cj.xh = x.xh and rownum0 特别注意这样外层查询时由于内层...

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...

oracle使用rownum伪列可以实现分页,三表连接分页示例代码如下: select * from (select rownum r,k.kch,k.kcm,cj.cj,x.xh,x.xm from KCB k,CJB cj,XSB x where k.kch = cj.kch and cj.xh = x.xh and rownum0特别注意这样外层查询时由于内层查询...

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 ...

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...

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