- (Subtract) (Transact-SQL)

Článek
05/16/2013

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

Applies to: SQL Server (SQL Server 2008 through current version and Windows Azure SQL Database (Initial release through current release).

Topic link icon Transact-SQL Syntax Conventions

Syntax

-- Core Syntax (common to SQL Server and SQL Database)
expression - expression

Arguments

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.

Result Types

Returns the data type of the argument with the higher precedence. For more information, see Data Type Precedence (Transact-SQL).

Examples

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.

Applies to: SQL Server and SQL Database.

USE AdventureWorks2012;
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.

Applies to: SQL Server and SQL Database.

USE AdventureWorks2012;
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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