CONCAT() function not working

[CybJunior]

Hi,
I have a problem using the CONCAT function. If i set the column comments to not null, it wont create a user. If i set it to Null, it wont add new comments if there are no comments in the row yet(it works only if they are there). What's the problem with not null parameter?
The query is:

SET comments = CONCAT(comments, '\n', '".$_POST['comments2']."')  WHERE customer_id='".$customer."' LIMIT 1";

Thanks
Alexey

[Roger_Ramjet]

I guess your comments column is text or blob type, and they can't have a default value. So you need to insert something into it when creating a new user if it is set to not null. Now, you can try inserting a space or an empty string as the value - not sure how mysql handles those, not something that has arrisen for me since mine are all filled with existing data from backoffice dbs and I make such columns nullable.

If the empty string does not work then you need to look at using CASE in your update query to overcome the concat null problem. On second thoughts you should be using CASE anyway.

would be

$sql = "UPDATE users SET comments =  CASE comments 
      WHEN null THEN '".$_POST['comments2']."'
      ELSE CONCAT(comments, '\n' , '".$_POST['comments2']."')
      END
      WHERE customer_id='".$customer."' LIMIT 1";

Makes it much neater as you don't get a newline before the first comment.