Question

In C# or any other similar languages, if we use a magic number, it is bad practice. How about SQL? I have seen this type of SQL a lot:

CREATE PROCEDURE ProcessOrder
    @productTypeId   INT
    , @productName   NVARCHAR(50)  
AS
BEGIN

    IF (@productType = 3) -- Electronic product type 
        -- Handle electronic
    ELSE IF (@productType = 4) -- Other product type     

END     

The user call this with an ENUM which converted to INT. Assuming ProductType table (3, ‘Electronic’) exist.
What should be the best practice here?

Answer 1

You can always use functions.

CREATE FUNCTION
    [dbo].PRODUCT_ELECTRO()
RETURNS INT
AS
BEGIN
        RETURN 3
END


-- This returns the value 3
SELECT
    dbo.PRODUCT_ELECTRO()

IF @MyValue = dbo.PRODUCT_ELECTRO()
BEGIN
    PRINT 'The value is tres'
END