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If I want to test a calculation to be used in an SQL SELECT statement I can use variables to allow me to use several test values without rewriting the calculation.
DECLARE @GrossPrice DECIMAL(18,2)
DECLARE @VATRate DECIMAL(18,2)
SET @GrossPrice = 100
SET @VATRate = 0.2
SELECT
@GrossPrice AS [Sale Price]
,@GrossPrice/(1+@VATRate) AS [Net Price]
,@GrossPrice - @GrossPrice/(1+@VATRate) AS [VAT]
Here is the output with three columns appropriately aliased.
The results of the calculations
In practice I would have CAST the results to DECIMAL(18,2) as well.
Once you are happy with the calculations a little bit of editing will allow it to be used on a real table.
SELECT
GrossPrice AS [Sale Price]
,GrossPrice/(1+VATRate) AS [Net Price]
,GrossPrice - GrossPrice/(1+VATRate) AS [VAT]
FROM tblSale
I am assuming tblSale had two columns with names almost identical to the variables and three rows of data.
The results of the calculation on a table
I hope the above methods help you write and test calculations in SQL with any data you want rather than being limited to the data in your test tables.
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