concat两次写入数据

Question

Here is my query:

mysql_query ("UPDATE p_candidate SET  `med_comt` = CONCAT_WS(`med_comt`,' ','$_POST[med_comt]') where `candidate_id` = '$_POST[candidate_id]'");

what I am trying to do is use concat so that the new comments are added to the database without overwriting existing comments.

The new comments are not being separated by a space and the new comments get written twice. for example if the existing comment is 'this is a test' and the new comment is 'another one!'

the new data looks like this

this is a testanother one!another one!

what I want is :

this is a test another one!

It would be better if I could get the new comment on a new line like this:

this is a test

another one!

Thanks

Answer 1

You're using CONCAT_WS as if it were CONCAT. CONCAT_WS works differently. Your first argument should be the SEPARATOR, and your remaining arguments are the values which get split via the SEPARATOR.

mysql_query ("UPDATE p_candidate SET  `med_comt` = CONCAT_WS(' ', `med_comt`, '$_POST[med_comt]') where `candidate_id` = '$_POST[candidate_id]'");

PS: Please sanitize or prepare your data.