SQL Server Team-based Development - Red Gate Software

-- being defensive, we must drop the old implementation
-- so that reporting periods are implemented
-- only in one place
DROP FUNCTION dbo.MonthReportingPeriodStart ;
GO
CREATE FUNCTION dbo.MonthReportingPeriodStart
( @AsOfDate DATETIME )
RETURNS DATETIME
AS
BEGIN ;
DECLARE @ret DATETIME ;
SET @ret = DATEADD(day, -29, @AsOfDate) ;
RETURN @ret ;
END ;
Listing 6-10: Scalar UDF which implements the definition of reporting period.
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Chapter 6: Reusing T-SQL Code
We also have to change our SalesForMonth function, so that it utilizes our new scalar
UDF, as shown in Listing 6-11.
ALTER FUNCTION dbo.SalesForMonth ( @AsOfDate DATETIME )
RETURNS TABLE
AS
RETURN
( SELECT SalesID ,
StateCode ,
SaleDateTime ,
Amount
FROM dbo.Sales AS s
WHERE SaleDateTime >=
dbo.MonthReportingPeriodStart(@AsOfDate)
AND SaleDateTime