Can a DATETIME Value Be Subtracted from Another DATETIME Value in SQL Server Transact-SQL?

Can a datetime value be subtracted from another datetime value? The answer is yes. The subtract operation can be performed by the subtract operator (-) as:

• datetime1 - datetime2: Returning a DATETIME value calculated as CONVERT(DATETIME, CONVERT(NUMERIC(18,9),datetime1) - CONVERT(NUMERIC(18,9),datetime2)).

The tutorial exercise below shows you some good examples:

DECLARE @birth_date DATETIME;
DECLARE @today_date DATETIME;
SET @birth_date = '2000-02-29 16:00:00.000';
SET @today_date = '2007-05-19 22:00:00.000';
SELECT @today_date - @birth_date;
GO
1907-03-22 06:00:00.000

DECLARE @birth_date DATETIME;
DECLARE @today_date DATETIME;
DECLARE @age NUMERIC(9,2);
SET @birth_date = '2000-02-29 16:00:00.000';
SET @today_date = '2007-05-19 22:00:00.000';
SET @age = CONVERT(NUMERIC(9,2), @today_date - @birth_date);
SELECT @age;
GO
2636.25

⇒ Date and Time Functions Supported by SQL Server 2005 in SQL Server

⇐ Converting DATETIME and NUMERIC Values in SQL Server

⇑ Date/Time Operations and Functions in SQL Server Transact-SQL

⇑⇑ SQL Server Transact-SQL Tutorials