PHP MYSQL if null statement

I need a way t开发者_如何转开发o do this, If a mysql query dosn't retrieve any data, something happens. Here's an example.

$color="red";
$query = mysql_query("SELECT * FROM people WHERE shirt='$color'");
if($query = null){
echo 'No people wearing '.$color' shirts available.';
}

---

Use mysql_num_rows() for this.

if( mysql_num_rows($query) == 0 ) {
    // No results returned

---

Use mysql_num_rows to check, how many rows have been returned by your query.

<?php

$link = mysql_connect("localhost", "mysql_user", "mysql_password");
mysql_select_db("database", $link);

$result = mysql_query("SELECT * FROM table1", $link);
$num_rows = mysql_num_rows($result);

if( $num_rows == 0 ) {
    // No results returned
    echo "No results!";
} else {
    echo "$num_rows Rows\n";
}

?>

---

Besides the mysql_num_rows() there is also COUNT() which could be used like this:

"SELECT COUNT(*) FROM people WHERE shirt='$color'"

You might actually need more data from the database but if you only need a number then this would remove the need for an if.

---

You could use empty either:

$num_rows = mysql_num_rows($result);

if(empty($num_rows)){
    echo 'No results';
}