a表 aid,aname (a主表)
b表 aid,cid (存储a表与b表的多对多关系)
c表 cid,cname (c主表)
d表 cid,eid (存储c表与e表的多对多关系)
e表 eid,ename (e主表)做内联接式验,都成功(不包括NULL)
select a.*, b.*, c.* from
a inner join
(b inner join c
on b.cid = c.cid)
on a.aid = b.aidselect c.*, d.*, e.* from
c inner join
(d inner join e on d.eid = e.eid )
on c.cid = d.eid当把上面的整合起来时,无数据显示,请问如何解决?select a.*, c.*, e.* from
a inner join
(b inner join
(c inner join
(d inner join e on d.eid = e.eid )
on c.cid = d.eid)
on b.cid = c.cid)
on a.aid = b.aid
b表 aid,cid (存储a表与b表的多对多关系)
c表 cid,cname (c主表)
d表 cid,eid (存储c表与e表的多对多关系)
e表 eid,ename (e主表)做内联接式验,都成功(不包括NULL)
select a.*, b.*, c.* from
a inner join
(b inner join c
on b.cid = c.cid)
on a.aid = b.aidselect c.*, d.*, e.* from
c inner join
(d inner join e on d.eid = e.eid )
on c.cid = d.eid当把上面的整合起来时,无数据显示,请问如何解决?select a.*, c.*, e.* from
a inner join
(b inner join
(c inner join
(d inner join e on d.eid = e.eid )
on c.cid = d.eid)
on b.cid = c.cid)
on a.aid = b.aid
a inner join b on a.aid=b.aid innser join c on b.cid=c.cid
innser join d on c.cid=d.eid inner join e on d.eid=e.eid
a inner join b on a.aid=b.aid inner join c on b.cid=c.cid
inner join d on c.cid=d.eid inner join e on d.eid=e.eid
select a.*,c.* from a
inner join b on a.aid=b.aid
inner join c on b.cid=c.cid
inner join d on c.cid=d.eid <--- 内联d表时,无记录(d表为c表与e表的多对多关系表)请解释为什么不使用嵌套的方法
b表 aid,cid (存储a表与b表的多对多关系)
c表 cid,cname (c主表)
d表 cid,eid (存储c表与e表的多对多关系)
e表 eid,ename (e主表) a表: b表: c表 d表 e表
aid,aname aid,cid cid, canme cid, eid eid,ename
1 张三 1 1 小编 1 2 1 删除新闻贴
2 李四 1 2 总编 2 1 2 发新闻贴
3 王五 2 3 经理 2 2 3 加奖金
3 3 3我想完整显检索出每个用户所属的角色和角色所拥有的权限(不包括空值)
下面使用嵌套方法,发见当嵌套d表时,面前嵌套检索出来的记录都不见了select a.*, c.*, e.* from
a inner join
(b inner join
(c inner join
(d inner join e on d.eid = e.eid ) <<-- 嵌套这行是记录就不完了,请问为什么
on c.cid = d.eid)
on b.cid = c.cid)
on a.aid = b.aid
aid,aname aid,cid cid,canme cid,eid eid,ename
1 张三 1 2 1 小编 1 2 1 删除新闻贴
2 李四 1 3 2 总编 2 1 2 发新闻贴
3 王五 2 1 3 经理 2 2 3 加奖金
3 1 3 3