mySQL function problem

I wrote this function to get the number of rows in the table for each particular category. I wrote this function, it won't work, and I can't figure out why.

function getNumRows($category){
$query = "SELECT * FROM direc WHERE category=\"$category\"";
$result = mysqli_query($cxn,$query);
if($result){
echo 'query successful';
}
else{
echo 'query failed';
}
$num = mysqli_num_rows($result);
return $num;
}

I know that $cxn works, so the problem must be with the $query. but I tried the syntax on the mySQL command line and it worked, so what gives here? what is wrong with this function?

 

nevermind, I figured it out. I had to add the $cxn as an argument to the function.