How to avoid underscore in PATINDEX template argument?

Question

I found a solution for finding underscore position with PATINDEX:

DECLARE @a VARCHAR(10) SET @a = '37_21' PRINT PATINDEX('%_%', @a) -- return 1 (false) PRINT PATINDEX('%!%', REPLACE(@a, '_', '!')) -- return 3 (correct) 

Do you have any other ideas? How to escape the underscore?

Answer 1

I always did this with parentheses: '%[_]%'

Answer 2

To combine two underscores, each of them will be enclosed in brackets

 '%[__]%' -- matches single _ with anything after '%[_][_]%' -- matches two consecutive _ 

Answer 3

You can avoid using the characters [ and ] :

PRINT PATINDEX('%[_]%', '37_21')