Question

I am having a problem with a database join query and I am looking for someone to help me out.

Basically I’ve got two tables, Invoices and Receipts.

Invoices

Invoice ID
Amount
Date_Added

Receipts

ReceiptID
InvoiceID
Amount
Date_Added

The thing is that I need to produce a table like below, but I have multiple records in Receipts and I am pretty sure that the data is stored in a good way, just not exactly sure what the query would be.

InvoiceID   RecieptID    Amount     Balance     Date_Added
1           0            100.00     100.00      01.05.2012
1           1            100.00     0.00        02.05.2012
2           0            250.00     250.00      03.05.2012
3           0            100.00     350.00      04.05.2012
2           2            100.00     250.00      05.05.2012

Does this make sense? So it should be in date order. So effectively I can see line by line what is going on each date.

Answer 1

Setup:

USE tempdb;
GO

CREATE TABLE dbo.Invoices
(
  InvoiceID INT,
  Amount DECIMAL(12,2),
  DateAdded SMALLDATETIME
);

CREATE TABLE dbo.Receipts
(
  ReceiptID INT,
  InvoiceID INT,
  Amount DECIMAL(12,2),
  DateAdded SMALLDATETIME
);

SET NOCOUNT ON;

INSERT dbo.Invoices SELECT 1, 100, '20120501'
UNION ALL SELECT 2, 250, '20120503'
UNION ALL SELECT 3, 100, '20120504';

INSERT dbo.Receipts SELECT 1, 1, 100, '20120502'
UNION ALL SELECT 2, 2, 100, '20120505';

Query:

;WITH x AS 
(
  SELECT InvoiceID, ReceiptID, Amount, DateAdded, 
   rn = ROW_NUMBER() OVER (ORDER BY DateAdded)
  FROM
  (
    SELECT InvoiceID, ReceiptID = 0, Amount, DateAdded
    FROM dbo.Invoices -- where clause?
    UNION ALL 
    SELECT InvoiceID, ReceiptID, Amount, DateAdded
    FROM dbo.Receipts -- where clause?
  ) AS y
),
z AS
(
  SELECT xrn = x.rn, x.InvoiceID, x.ReceiptID, x.Amount, x.DateAdded, 
    PlusMinus = CASE WHEN x.ReceiptID > 0 THEN -x.Amount ELSE x.Amount END
    FROM x LEFT OUTER JOIN x AS x2
    ON x.rn = x2.rn + 1
)
SELECT InvoiceID, ReceiptID, Balance = (
  SELECT SUM(COALESCE(PlusMinus, Amount)) 
  FROM z AS z2 
  WHERE z2.xrn <= z.xrn
), Amount, DateAdded
FROM z
ORDER BY DateAdded;

Cleanup:

DROP TABLE dbo.Invoices, dbo.Receipts;