REPLACE and IF in expression causes concatenation from previous row - mysql

Question

The following sql statement:
SELECT
profile_pic
FROM
(`member`)
WHERE
`active` = 1
produces the following result:
profile_pic
1_1345694557.jpg
<blank_value>
<blank_value>
<blank_value>
I want the "blank values" to default to "no_prof_thumb.jpg".
So I created this statement:
SELECT
REPLACE(IF (CHAR_LENGTH(profile_pic) > 0, profile_pic, 'no_prof.jpg' ), '.jpg', '_thumb.jpg') AS profile_pic
FROM
(`member`)
WHERE
`active` = 1
Here is the result:
profile_pic
1_1345694557_thumb.jpg
no_prof_thumb.jpg
no_prof_thumb_thumb.jpg
no_prof_thumb_thumb_thumb.jpg
Why does _thumb keep appending itself to the value in the previous row?
How should I fix my expression?
Update
This issue occurs on a GoDaddy mySQL database. I reproduce when it connecting remotely through SQLyog and when I log into GoDaddy and run it through phpMyAdmin.
However, I cannot reproduce locally nor on sqlFiddle.
So it must be some kind of configuration issue.

Answer 1

You needed to use IF outside the REPLACE statement like this.
SELECT
IF (profile_pic = '', 'no_prof.jpg',
REPLACE(profile_pic, '.jpg', '_thumb.jpg')) AS profile_pic
FROM
(`member`)
WHERE
`active` = 1
You can also use CASE statement instead of IF like this:
SELECT
CASE profile_pic
WHEN '' THEN 'no_prof.jpg'
ELSE REPLACE(profile_pic, '.jpg', '_thumb.jpg')
END AS profile_pic
FROM member
WHERE active = 1;
See this fiddle

Answer 2

The nested logic is a little weird. You can simplify it with a CASE statement. If the value is an empty string, just return no_prof_thumb.jpg. Otherwise, replace .jpg with _thumb.jpg.
SELECT
CASE
WHEN profile_pic = '' THEN 'no_prof_thumb.jpg'
ELSE REPLACE(profile_pic, '.jpg', '_thumb.jpg')
END AS profile_pic
FROM member
WHERE active = 1
I can't, explain why you're getting the weird result you're getting without further testing though.