检查mysql中是否已存在行

Question

quick question:

How to check if row already exists in mysql?

I know some will suggest mysql_num_rows(), which I've tried and no good.

Here's the PHP code:

...

$chk = mysql_query("SELECT * FROM f_table WHERE f = '$id' AND h = 'h' AND status = '1'");

if(mysql_num_rows($chk) > 0){
    $msg = 'exist';
}else{
            $msg = 'gotta';
    }

Ps: I just noticed that the php manual suggested us to use some else instead of 'mysql_num_rows()', and my mysql version is 5.0. Is it related?

Thank u for ur time.

Answer 1

Typically you'd want to let MySQL do the counting instead of fetching all rows. MySQL can use indexes and doesn't have to retrieve all data, which may be a lot more efficient:

$result = mysql_query('SELECT COUNT(*) as `count` FROM ...') /* or die(mysql_error()) */;
$row = mysql_fetch_assoc($result);

if ($row['count'] ...)