Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given [duplicate]
I get this error whenever I run this:
Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given
The Code:
$amn = mysql_query("SELECT * FROM `Messages` WHERE to_user='$usr' AND read='0'");
print_r(mysql_num_rows($amn));
That's because mysql_query sometimes returns boolean false (query error). You need to check it:
$amn = mysql_query("SELECT * FROM `Messages` WHERE to_user='$usr' AND read='0'");
if($amn === false) {
var_dump(mysql_error());
}
else {
print_r(mysql_num_rows($amn));
}
Code above is written in bad style and deprecated. Use PDO with Exceptions in real projects.