Be aware when you use two digit year in date

When you execute the below query, as you expect, the result will be “September 26th 2049”

DECLARE @DATE AS DATETIME 
SET @DATE = '09/26/49' 
SELECT @DATE

Now, Lets see what happen when we pass 50 instead of 49

DECLARE @DATE AS DATETIME 
SET @DATE = '09/26/50' 
SELECT @DATE

You will get the result as “September 26th 1950”; this is because by default, SQL Server interprets two-digit years based on a cutoff year of 2049.

DECLARE @DATE AS DATETIME 
SET @DATE = '09/26/2050' 
SELECT @DATE

Now, as you expect you will get the result as “September 26th 2050”; so it is always good to specify the four-digit year.

Notes from BOL

By default, SQL Server interprets two-digit years based on a cutoff year of 2049. That is, the two-digit year 49 is interpreted as 2049 and the two-digit year 50 is interpreted as 1950. Many client applications, such as those based on Automation objects, use a cutoff year of 2030. SQL Server provides the two digit year cutoff configuration option that changes the cutoff year used by SQL Server and allows for the consistent treatment of dates. We recommend specifying four-digit years.”