add to existing value in mysql column using CONCAT function?

Question

trying to add text to an existing value in mysql using mysql's concat function?

so existing value is currently 'john' and after function has run will be 'johnewvalue'

i am trying to add a piece of text ':reply' to the existing text which is in my subject column in my database ptb_messages.

i am trying to do this using mysql's concat function but im not getting any result what so ever.

$sql = mysql_query("UPDATE ptb_messages SET subject = CONCAT subject, 'newvalue' WHERE id='".$message_id."'"); 

can someone please show me a way of getting it to do what i want. thanks.

Answer 1

it should be

UPDATE ptb_messages 
SET subject = CONCAT( subject, 'newvalue')
WHERE ... 

• MySQL CONCAT

in PHP

$sql = mysql_query("UPDATE ptb_messages SET subject = CONCAT(subject, 'newvalue') WHERE id='".$message_id."'"); 

As a sidenote, the query is vulnerable with SQL Injection if the value(s) of the variables came from the outside. Please take a look at the article below to learn how to prevent from it. By using PreparedStatements you can get rid of using single quotes around values.

• How to prevent SQL injection in PHP?