检查数据库中是否存在数据

Question

What is the right way of checking if the required data is in the database?

What I use currently is,

mysql_query("SELECT anyfield FROM table WHERE field='$data'");

and then check the if any rows are affected.

But I dont really have any use with the extracted data anyfield. Eventhough the resource usage is so minor here, what is the right way to check if data exists in a db without extracting any other fields from the table?

Answer 1

Let the database count and retrieve the count data from the query.

$result = mysql_query('SELECT COUNT(*) FROM `table` WHERE `field` = ...');
if (!$result) {
    die(mysql_error());
}
if (mysql_result($result, 0, 0) > 0) {
    // some data matched
} else {
    // no data matched
}