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Remove comments from the SQL Code

By Shivaram Challa,


This function takes in a varchar(max) as input and strips out all the comments and RETURNS that string. It replaces comments with a carriage return character; this behavior can be easily changed by find/replacing the char(13) in the code to a single space ' '.


  • Returns text with out any comments in it.
  • Handles commet like "--"
  • Handles comments like /* some text */

/* some text

/* some text */

some more text


Usage Example:

USE tempdb

DECLARE @def varchar(100) = '
hello /* first */ hell0 2 /* second /* third */-second */ --third
PRINT dbo.UtilFn_RemoveComments (@def)

Algorithm Logic:

1. Handling nested /*..*/ type comments 

Start a while look; while loop exits if it can't find anymore /* in the input string:
1a. Find the first ending '*/'
1b. Truncate everything after that
1c. Reverse the string and find the first occurance of '*/' again; since the string is reversed, we;d have to look for */ instead of /*
1d. Calculate the comment length
1e. Replace comment with char(13)

1f.  repeat until you can't find any more /*

2. Handling '--' type comment 

2a. Find starting point of '--' 

2b. Get the entire string length after that

2c. Replace comment with char(13)

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