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- (Subtract) (Transact-SQL)

Subtracts two numbers (an arithmetic subtraction operator). Can also subtract a number, in days, from a date.

Topic link icon Transact-SQL Syntax Conventions


expression - expression

expression

Is any valid expression of any one of the data types of the numeric data type category, except the bit data type. Cannot be used with date, time, datetime2, or datetimeoffset data types.

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 the state or province with the highest tax rate and the state or province with the lowest tax rate.

USE AdventureWorks2008R2;
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 datetime date.

USE AdventureWorks2008R2;
GO
DECLARE @altstartdate datetime;
SET @altstartdate = CONVERT(DATETIME, ''January 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)

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