我有这两个表
#TABLE1#
##CompanyName## ##PrimaryKey##
DELL 1
DELL CALIFORNIA 2
DELL SAN FRANCISCO 3
DELL LOS ANGELES 4
IBM 5
GOOGLE 6
#TABLE2#
##ParentComp## ##ParentPrimaryKey## ##ChildComp## ##ChildPrimaryKey##
DELL 1 DELL CALIFORNIA 2
DELL CALIFORNIA 2 DELL SAN FRANCISCO 3
DELL CALIFORNIA 2 DELL LOS ANGELES 4
现在预期的表格如下所示;关系(层次结构)列只有三个可能的值(PARENT / CHILD / INDEPENDENT),如下所示:
#TABLE3#
##CompanyName## ##Relationship## ##ParentCompany##
DELL PARENT ---
DELL CALIFORNIA CHILD DELL
DELL SAN FRANCISCO CHILD DELL CALIFORNIA
DELL LOS ANGELES CHILD DELL CALIFORNIA
IBM INDEPENDENT ---
GOOGLE INDEPENDENT ---
我已经尝试过以下两个加入选项
选择
...
表1
左外连接
Table2 ON Table1.PrimaryKey = Table2.ParentPrimaryKey
左外连接
表2 tAlias2
Table2.ParentPrimaryKey = tAlias2.ChildPrimaryKey
返回
##CompanyName## ##Relationship## ##ParentCompany##
DELL PARENT ---
DELL CALIFORNIA CHILD DELL
DELL SAN FRANCISCO INDEPENDENT ---
DELL LOS ANGELES INDEPENDENT ---
IBM INDEPENDENT ---
GOOGLE INDEPENDENT ---
或
选择
...
表1
左外连接
Table2 ON Table1.PrimaryKey = Table2.ChildPrimaryKey
左外连接
表1 tAlias1
Table2.ParentPrimaryKey = tAlias1.PrimaryKey
会返回这样的内容:
##CompanyName## ##Relationship## ##ParentCompany##
DELL INDEPENDENT ---
DELL CALIFORNIA CHILD DELL
DELL SAN FRANCISCO CHILD DELL CALIFORNIA
DELL LOS ANGELES CHILD DELL CALIFORNIA
IBM INDEPENDENT ---
GOOGLE INDEPENDENT ---
答案 0 :(得分:0)
加入talias2.ChildPrimaryKey
后,您需要加入Table1.PrimaryKey
列。
SELECT ..
FROM table1
LEFT OUTER JOIN table2
ON table1.primarykey = table2.parentprimarykey
LEFT OUTER JOIN table2 talias2
ON table1.primarykey = talias2.childprimarykey --here
当您使用tAlias2.ChildPrimaryKey
加入table2.parentprimarykey
时,只有来自table2
和table1
(table1.primarykey = table2.parentprimarykey
)的匹配记录才能加入tAlias2.ChildPrimaryKey
答案 1 :(得分:0)
您的架构显然是多余的。您可以删除table2
并从以下内容中获得所需内容。
declare @tbl table (CompanyName varchar(100),PrimaryKey int primary key, parentId int)
insert @tbl values
('DELL', 1,null),
('DELL CALIFORNIA', 2,1),
('DELL SAN FRANCISCO', 3,2),
('DELL LOS ANGELES', 4,2),
('IBM', 5,null),
('google', 6,null)
;with tbl as (
select PrimaryKey, CompanyName, parentId,
rel = cast(case when exists(select 1 from @tbl t1 where t1.parentId=t.PrimaryKey) then 'parent'
else 'independent' end as varchar(100)),
cast(null as varchar(100)) parentName
from @tbl t
where t.parentId is null
union all
select t.PrimaryKey, t.CompanyName, t.parentId,cast('child' as varchar(100)),
tbl.CompanyName
from @tbl t inner join tbl on t.parentId=tbl.PrimaryKey
)
select * from tbl
order by PrimaryKey