数据库：检查重复错误

Question

I have a PHP code and a field in the database which is a unique field. If people fill in the form and if the $_POST['name'] is already in the database it gives an error.

That's what I have and want, but now I want to check if there's an error so I can handle it in a if / else statement.

This is my code:

$db = new database();
$sql = "INSERT INTO product_groepen (name) VALUES (".$_POST['name'].")";
$result = $db->executeQuery($sql);
if ($result)
{
    $db->executeQuery($sql);
    $page .= 'Yes';
} else {
    $page .= 'No';
}

The error:

Warning: PDO::query() [pdo.query]: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry 's' for key 2 in /classes/database.class.php on line 26

It works, and when it isn't working it says 'no', but the error remains.

Answer 1

try with INSERT IGNORE to ignore insert if it's duplicate. Also if you are still using mysql_* you have an mysql injection vulnerability, escape it:

$db = new database();
$sql = "INSERT IGNORE INTO product_groepen (name) VALUES ('".mysql_real_escape_string($_POST['name'])."')";
$result = $db->executeQuery($sql);
$affected = mysql_affected_rows($result); // you must have that function something like $db->affectedRows ?
if ($affected){
    $page .= 'Yes';
} else {
    $page .= 'No';
}

and make sure you don't execute the query twice