Joins and Loops in SQL Server 2008 - sql

Question

How to join the below tables to get result like in "Result" table:
Table: Invoice
Inv_No Fk_Rep_ID Inv_Date Inv_Amt
3000 202 10/1/2014 35
3001 194 11/1/2014 40
3002 180 15/1/2014 55
Table :Return
Return_ID FK_Rep_ID Ret_Date Ret_Amt
2000 202 17/1/2014 67
2001 194 15/1/2015 43
Table: Credit
Credit_ID FK_Rep_ID credit_Date credit_Amnt
1000 NULL 4/2/2014 60
1001 202 5/2/2014 12
Table: Debit
Debit_ID FK_Rep_ID Debit_Date Debit_Amnt
400 NULL 4/5/2014 600
4001 194 5/5/2014 110
Table:Receipt_Items
Fk_Rec_No FK_Item_No Item_Type Rec_Item_ID
7787 1000 2 1
7788 2000 1 1
7788 3000 0 2
7788 3001 0 3
7788 3002 0 4
7788 4000 3 5
7788 4001 3 6
7789 1001 2 1
Table :Sales_Rep
Rep_ID Rep_Name
180 Vinu
194 Bibin
202 Salman
Result
Fk_Rec_No Fk_Item_No Item_Type Rep_Name Item_Date Item_Amt
7787 1000 Credit NULL 4/2/2014 -60
7788 2000 Return salman 15/1/2014 -67
7788 3000 Invoice salman 10/1/2014 35
7788 3001 Invoice Bibin 11/1/2014 40
7788 3002 Invoice Vinu 12/1/2014 55
7788 4000 Debit NULL 4/5/2014 600
7788 4001 Debit Bibin 5/5/2014 110
7789 1001 Credit Salman 5/2/2014 -12
Query :
SELECT tt.*,SR.Rep_Name
FROM(SELECT
fk_receipt_no
,fk_item_no
,CASE Item_type
WHEN 0 THEN 'INVOICE'
WHEN 1 THEN 'Return'
WHEN 2 THEN 'Credit'
WHEN 3 THEN 'Debit'
END as ITEM_type,
Case Item_type when 1 then '-'+Cast(Item_Amnt as varchar(50))
when 2 then '-'+Cast(Item_Amnt as varchar(50))
else Cast(Item_Amnt as varchar(50)) End Item_Amnt
,COALESCE(R.FK_Rep_ID,C.FK_Rep_ID,I.FK_Rep_ID) as FK_Rep_ID
,COALESCE(R.Ret_Date,C.Note_Date,I.Inv_Date) as Item_Date
FROM Recp_Item RI LEFT JOIN [Return] R ON RI.FK_Item_no=R.Return_ID
LEFT JOIN Credit C ON RI.FK_Item_No=C.Note_ID
LEFT JOIN Invoice I ON RI.FK_Item_No=I.Inv_No
) tt LEFT JOIN [Sales Rep] SR ON SR.Rep_ID=tt.FK_Rep_ID

Answer 1

You probably should mention that FK_Item_No refers sometimes to different things, like Credit_ID. This kind of multipurpose FK almost always results in a union for each type of item it could represent.
This is pseudo code, I expect you to provide all the tedious join criterias since you should be capable of doing so.
Notice left joins are used to the Rep table since you have some null FK's
In each select aliases are used to normalize the column names such as credit_amnt => Item_Amt. Technically this is only required for the first select in the join so long as the others are in the same order, but I usually do it for all unions for readability.
Select * From
(
Select ri.Fk_Rec_No, Credit_ID as Fk_Item_No, it.Name as Item_Type,
r.Rep_Name, c.credit_Date as Item_Date, c.credit_Amnt as Item_Amt
From Credit c inner join Receipt_Items ri left join Rep r
--join with your item type table you don't show
Union
Select ri.Fk_Rec_No, Debit_ID as Fk_Item_No, it.Name as Item_Type,
r.Rep_Name, c.Debit_Date as Item_Date, d.Debit_Amnt as Item_Amt
From Debit d inner join Receipt_Items ri left join Rep r
--join with your item type table you don't show
Union
...
) as typesUnion
Order By Fk_Rec_No, Fk_Item_No