mysql在使用alter table时是否需要真正转义？

Question

I noticed the other day that I cannot bind variables when using PDO with ALTER TABLE for example the following example will not work,

$q = $dbc -> prepare("ALTER TABLE emblems ADD ? TINYINT(1) UNSIGNED NOT NULL DEFAULT '0', ADD ? DATETIME NOT NULL"); 
$q -> execute(array($emblemDB, $emblemDB . 'Date')); 

So is it necessary to use mysql_real_escape string and do it like below,

// ESCAPE NAME FOR MYSQL INSERTION
$emblemDB = mysql_real_escape_string($emblemDB);
// INSERT EMBLEM DETAILS INTO DATABASE
$q = $dbc -> prepare("ALTER TABLE emblems ADD " . $emblemDB . " TINYINT(1) UNSIGNED NOT NULL DEFAULT '0', ADD " . $emblemDB . "Date DATETIME NOT NULL");
$q -> execute();

Or do I not need to add in mysql_real_escape_string ? As the only thing the query can do is ADD columns?

Thanks

Answer 1

Depends. If you directly use user input in your query, you should use it. If you don't, the user could delimit the query and throw a DROP statement after it.

When a user would input:

somekindofname TINYINT(1) UNSIGNED NOT NULL DEFAULT '0'; DROP TABLE emblems --

Your query would become:

ALTER TABLE emblems ADD somekindofname TINYINT(1) UNSIGNED NOT NULL DEFAULT '0'; DROP TABLE emblems -- TINYINT(1) UNSIGNED NOT NULL DEFAULT '0', ADD TINYINT(1) UNSIGNED NOT NULL DEFAULT '0' somekindofname; DROP TABLE emblems -- Date DATETIME NOT NULL

Your database will execute the ALTER TABLE , execute the DROP TABLE and ignore the comment at the end.