mysql_query update value 2 by 2

Question

when i run the below mysql query in mysql front end the value increase by one:

Query: update tableName set ColA=ColA+1

previous value: 12
value after running query(1st time): 13
value after running query(2nd time): 14

But when i run the same query through my php script then it's always update 2 by 2.

<?php
mysql_query("update tableName  set ColA=ColA+1",$conn); 
?>

previous value: 12
value after running query(1st time): 14
value after running query(2nd Time): 16
value after running query(3rd Time): 18

why it's happening?

PHP Version 5.4.24
Mysql Version: 5.5.14
IIS version: 7

Answer 1

Use like this

mysql_query("update tableName  set `ColA`=ColA+1",$conn);

Or

mysql_query("update tableName  set `ColA`=`ColA`+1",$conn);

This is not MySQL issue but PHP. Single and Double Quotes are different...