SQL Server Error Severity Levels

Have you ever read the Severity Level indicated with an error occurred? Or just tried to find out the problematic code exist in your code for fixing it? It is always better to understand what error message says and its severity level because some errors cannot be fixed by us though it looks as fixable.

Severity level indicates the seriousness of the error, whether it can be ignored or not, whether it can be fixed by user level. Therefore we need to understand what it describes.

Range of the level	Description
0 to 9	Informational message, not an error. Warning for NULL usage in Average is a good example.
10	Informational message, it indicates non-severe error too.
11 to 16	Errors that can be fixed by us, such as syntax issues, deadlocks, permission related issues.
17 to 19	Serious software related error that user cannot correct. Out of memory, space are some of them.
20 to 24	Very serious errors related to either hardware or SQL Server itself. Generally, errors starting with level 19 gets logged in the Application log.
25	Same as above but this terminates SQL Server service.

Here are some examples;

USE AdventureWorks2014;
GO

-- Warning messages 0 - 10
SELECT COUNT(Color) FROM Production.Product;
GO

-- Errors form 11 - 16
SELECT * FRM Production.Product;
GO

-- Throwing an error with higher severity level
-- Note that 60005 is a user-defined message
RAISERROR (60005, 25, 1) WITH LOG;