How to replace only the first specified character in a string and leave other occurrence of the character alone.

Question

Hello my Friends:
I have a string that looks like this in a column:
Hello, World, Hello, Planet
I want to replace only the first occurrence so that the result looks like this:
Hello World, Hello, Planet
Working on some bad data source.
I need to replace the character regardless of it's location as long as it is the first.
I tried something like this, but I soon discovered that if the comma or character is missing the the string may get truncated or altered. If there are no characters in the string, then I want to simply leave it alone.
Here is where I am at:
DECLARE @MyValue NVARCHAR(MAX) = 'Hello, World, Hello, Planet';
SELECT MyString = STUFF('Hello, World', CHARINDEX(',', @MyValue, 0), 1, ' ');
Thanks my friends.

Answer 1

I have a string that looks like this in a column:
Hello, World, Hello, Planet
Why doesn't it say Hello Kitty?
Oh, sorry about that. Anyway:
SELECT MyString = CASE WHEN CHARINDEX(',', @MyValue, 0) >= 1
                       THEN STUFF(MyString, CHARINDEX(',', @MyValue, 0), 1, ' ')
                       ELSE MyString
                 END;
Erland Sommarskog, SQL Server MVP, [email protected]
Erland, love you sense of humor!! :)
Thanks for the solution.