Mysqli_num_row expects parameter

Quote:

This is the problem:
Warning: mysqli_num_row expects parameter 1 to be mysqli_result, bool given on line 27

I Have something againts the SQL injetion in js

<?php

session_start();
if(isset($_SESSION['nombredelusuario']))
{
	header('location: home.php');
}

if(isset($_POST['ingre']))
{
	
	$dbhost="localhost";
	$dbuser="root";
	$dbpass="";
	$dbname="clini";
	
	$conn=mysqli_connect($dbhost,$dbuser,$dbpass,$dbname);
	if(!$conn)
	{
		die("No hay conexión: ".mysqli_connect_error());
	}
	
	$nombre=$_POST['name'];
	$pass=$_POST['pass'];
	
	$query=mysqli_query($conn,"Select * from clini where name = '".$nombre."' and pass = '".$pass."'");
	$nr=mysqli_num_rows($query); HERE IS THE PROBLEM
	
	if(!isset($_SESSION['nombredelusuario']))
	{
	if($nr == 1)
	{
		$_SESSION['nombredelusuario']=$nombre;
		header("location: home.php");
	}
	else if ($nr == 0)
	{
		echo "<script>alert('Usuario no existe');window.location= 'login.php' </script>";
	}
	}
}
?>