- (Subtract) (Transact-SQL)
Subtracts two numbers (an arithmetic subtraction operator). Can also subtract a number, in days, from a date.
expression - expression
Is any valid expression of any one of the data types of the numeric data type category, except the bit data type.
Returns the data type of the argument with the higher precedence. For more information, see Data Type Precedence (Transact-SQL).
A. Using subtraction in a SELECT statement
The following example calculates the difference in tax rate between state or province with the highest tax rate and the state or province with the lowest tax rate.
USE AdventureWorks; GO SELECT MAX(TaxRate) - MIN(TaxRate) AS 'Tax Rate Difference' FROM Sales.SalesTaxRate WHERE StateProvinceID IS NOT NULL; GO
You can change the order of execution by using parentheses. Calculations inside parentheses are evaluated first. If parentheses are nested, the most deeply nested calculation has precedence.
B. Using date subtraction
The following example subtracts a number of days from a
USE AdventureWorks; GO DECLARE @altstartdate datetime; SET @altstartdate = CONVERT(DATETIME, '01/10/1900 3:00 AM', 101); SELECT @altstartdate - 1.5 AS 'Subtract Date';
Here is the result set:
Subtract Date ----------------------- 1900-01-08 15:00:00.000 (1 row(s) affected)