When to use STUFF instead of REPLACE – SQL Server

The STUFF function in SQL Server ‘inserts’ a string into another string. It deletes a specified length of characters in the first string at the start position and then inserts the second string into the first string at the start position.

REPLACE on the other hand replaces all occurrences of a specified string value with another string value.

The STUFF function is useful when you are not sure of the characters to replace, but you do know the position of the character. I saw an excellent implementation of this function over here by GMastros and Even. Here’s the code with a practical usage of STUFF:

CREATE FUNCTION [dbo].[fn_StripCharacters]
(
    @String NVARCHAR(MAX),
    @MatchExpression VARCHAR(255)
)
RETURNS NVARCHAR(MAX)
AS
BEGIN
    SET @MatchExpression =  '%['+@MatchExpression+']%'

    WHILE PatIndex(@MatchExpression, @String) > 0
        SET @String = STUFF(@String, PatIndex(@MatchExpression,
@String), 1, '')

    RETURN @String

END

SELECT dbo.fn_StripCharacters('a1$%s#22d&39#f4$', '^a-z')
as OnlyAlphabets

OUTPUT