Use SQL statements to obtain the Microsoft SQL Server version

Today, I wrote a data dictionary generation tool to determine the version of Microsoft SQL Server and find some information, which is summarized as follows:

Method 1:
Select @ version
The result is as follows:

Microsoft SQL Server 2005-9.00.1399.06 (Intel x86) Oct 14 2005 00:33:37 copyright (c) 1988-2005 Microsoft Corporation Enterprise Edition on Windows NT 5.2 (build 3790: Service Pack 2)
Method 2:
Xp_msver productversion
The result is as follows:

Index	Name	Internal_value	Character_value
2	Productversion	589824	9.00.1399.06

Method 3:
Select serverproperty ('productversion ')
The result is as follows:
9.00.1399.06
Method 3 should be used for comparison. The first character can be used for determination.