Beginning Microsoft SQL Server 2008 ... - S3 Tech Training

Chapter 12: Stored Procedures
386
returning numbers and, instead, return a variable name that will make my code more readable by indicating
the nature of the error I’m returning.
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SET NOCOUNT ON;
-- Set up “constants” for error codes
DECLARE @BUSINESS_ENTITY_ID_NOT_FOUND int,
@DUPLICATE_RATE_CHANGE int
SET @BUSINESS_ENTITY_ID_NOT_FOUND = -1000
SET @DUPLICATE_RATE_CHANGE = -2000
BEGIN TRY
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You may be curious as to why I’m using negative values here for my errors. While there is no real
standard on such things, I tend to use positive values for return codes that are informational in nature
(perhaps there are multiple possible successful outcomes and I want to indicate which successful outcome
occurred) and negative values for errors. You can find your own path on such things; just make sure you
follow the cardinal rule — be consistent! Also, I am deliberately not using the initialization syntax that
became available in SQL Server 2008 (I would change the declare to DECLARE @BUSINESS_ENTITY_
ID_NOT_FOUND int = -1000). This is purely for backward compatibility reasons, so adjust accordingly.
Next, we can test how many rows were affected by the UPDATE to HumanResources.Employee and utilize
that to detect a BusinessEntityID Not Found error:
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UPDATE HumanResources.Employee
SET JobTitle = @JobTitle,
HireDate = @HireDate,
CurrentFlag = @CurrentFlag
WHERE BusinessEntityID = @BusinessEntityID;
IF @@ROWCOUNT > 0
-- things happened as expected
INSERT INTO HumanResources.EmployeePayHistory
(BusinessEntityID,
RateChangeDate,
Rate,
PayFrequency)
VALUES (@BusinessEntityID, @RateChangeDate, @Rate, @PayFrequency);
ELSE
-- ruh roh, the update didn’t happen, so skip the insert,
-- set the return value and exit
BEGIN
PRINT ‘BusinessEntityID Not Found’;
ROLLBACK TRAN;
RETURN @BUSINESS_ENTITY_ID_NOT_FOUND;
END
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