PHP / MySQL：如果不存在则插入记录

Question

$sql = "INSERT INTO toplist 
       (serverName, serverPassword, serverIp, serverPort, serverBanner,
        serverShortDescription, serverDescription)
       VALUES
       ('$_POST[serverName]', '$_POST[serverPassword]', '$_POST[serverIp]',
        '$_POST[serverPort]', '$_POST[serverBanner]', 
        '$_POST[serverShortDescription]', '$_POST[serverDescription]')";

if (!mysql_query($sql, $con)) {
    die('Error: ' . mysql_error());
}

echo "The server " . $_POST[serverName] . "," . $_POST[serverIp] 
    . " has been added.";

mysql_close($con);

How can I make it so that if the entry "serverIp" does not already exist, it will add it to the database, if it does already exist, then it doesn't do anything. Also, will this be case sensitive too? Will you be able to bypass it bY tYpInG LiKe tHiS?

Answer 1

INSERT IGNORE ... will not insert if you have a unique constraint on your column. I would lower case the string before inserting it if you want it to be case insensitive.

http://dev.mysql.com/doc/refman/5.5/en/insert.html

This may also be helpful.