COALESCE不與加入

Question

我敢肯定有人對此有更好的想法，所以在這裏 - 我有一堆表格，其中有一堆表示其他表中的行的id（@tbLink）。我想在這裏表達

declare @tbLink table (linkid int, identitytypeid int, 
         itemid int, categoryid int,parentid int) 
declare @tbCat table (categoryid int, name varchar(20)) 
declare @tbId table (typeid int, typename varchar(20)) 
declare @tbDomain table (domainid int, domainname varchar(20)) 
-- 
declare @tbModule table (moduleid int, modulename varchar(20)) 
declare @tbProgram table (programid int, programname varchar(20)) 


INSERT INTO @tbLink VALUES (1, 1, 1, 1, 1) 
INSERT INTO @tbLink VALUES (2, 1, 1, 2, 1) 

INSERT INTO @tbCat VALUES (1, 'Program') 
INSERT INTO @tbCat VALUES (2, 'Module') 

INSERT INTO @tbId VALUES (1, 'Domain') 
INSERT INTO @tbId VALUES (2, 'Group') 

INSERT INTO @tbDomain VALUES (1, 'DEV') 

INSERT INTO @tbModule VALUES (1, 'Module1') 
INSERT INTO @tbProgram VALUES (2, 'ProgramA') 


select t.*, i.typename, c.name, d.domainname, COALESCE(m.modulename, p.programname) 
as objectname from @tbLink t 
inner join 
@tbId i on t.identitytypeid = i.typeid 
inner join 
@tbCat c on t.categoryid = c.categoryid 
inner join 
@tbDomain d on t.parentid = d.domainid 
left join 
@tbModule m on m.moduleid = t.itemid 
left join 
@tbProgram p on p.programid = t.itemid 

我的結果是：

1 1 1 1 1 Domain Program DEV Module1 
2 1 1 2 1 Domain Module DEV Module1 

但我期待第1行是「ProgramA」而不是「模塊1」 - 我失去了一些東西在這裏？這是否也正確使用了COALESCE？

乾杯

邁克

Answer 1

兩行有1

一個項目的ID我想你可能想加入他們的類ID和商品ID，改變ProgramA有programid of 1，並在你的加入：

left join 
@tbModule m on t.categoryid = 2 AND m.moduleid = t.itemid 
left join 
@tbProgram p on t.categoryid = 1 AND p.programid = t.itemid 

Answer 2

也許你應該考慮一個不同的設計。 Fo我猜你可以嘗試這些更改：

--declare @tbModule table (moduleid int, modulename varchar(20)) 
--declare @tbProgram table (programid int, programname varchar(20)) 
declare @tbItems table (itemid int, categoryid int, itemname varchar(20)) 

... 
--INSERT INTO @tbModule VALUES (1, 'Module1') 
--INSERT INTO @tbProgram VALUES (2, 'ProgramA') 
INSERT INTO @tbItems VALUES (1, 1, 'Module1') 
INSERT INTO @tbItems VALUES (1, 2, 'ProgramA') 

select t.*, i.typename, c.name, d.domainname, its.itemname 
as objectname from @tbLink t 
inner join 
@tbId i on t.identitytypeid = i.typeid 
inner join 
@tbCat c on t.categoryid = c.categoryid 
inner join 
@tbDomain d on t.parentid = d.domainid 
left join @tbItems its on its.categoryid = t.categoryid AND its.itemid = t.itemid 
--@tbModule m on m.moduleid = t.itemid 
--left join 
--@tbProgram p on p.programid = t.itemid