Question

I am trying to run the following query, but am getting a sql syntax error, but dreamweaver doesnt seem to be highlighting any error so im not sure where it is ?.
thanks 🙂

<?php
$form_id = $_POST[form_id];
    $query = mysql_query("
IF NOT EXISTS (SELECT * FROM INFORMATION_SCHEMA.COLUMNS
WHERE 
TABLE_NAME = 'email_history' 
AND COLUMN_NAME = `$form_id`)
BEGIN
 ALTER TABLE 'email_history' ADD `$form_id` VARCHAR( 255 ) NOT NULL
END;
") or die(mysql_error());
?>

Answer 1

Everyone has focused on bad quoting, but is there any chance of this query to run? Does MySQL allow such conditional statements? I know this is possible in stored routines but I have never heard of such direct usage, so I would split this into two queries: column existence check and table alteration.

This will look like this:

<?php
$form_id = some_function_to_check_if_input_is_valid_etc($_POST[form_id]);
$exist_result = mysql_query("SELECT IF(NOT EXISTS(
    SELECT * 
    FROM    INFORMATION_SCHEMA.COLUMNS
    WHERE   TABLE_NAME  = 'email_history' 
    AND     COLUMN_NAME = '{$form_id}'
    ),1,0) AS should_alter_table
");
$row = mysql_fetch_assoc($exist_result);
if($row['should_alter_table']){
    mysql_query("ALTER TABLE email_history ADD `{$form_id}` VARCHAR( 255 ) NOT NULL");
}