trying to check if user exists with php - php

Question

hi i am trying to make a php script that checks if a user is in the database only it gives me the error
mysqli_num_rows() expects parameter 1 to be mysqli_result, bool given in C:\xampp\htdocs\stage\userExist.php on line 22
below is the code
<?php
$link = mysqli_connect('localhost', 'root', '', 'k3462_top-tree');
$query = "SELECT * FROM users";
$userName = $_GET['userName'];
$result = mysqli_query($link, $query);
echo "<table>";
while($row = mysqli_fetch_array($result)){
echo "<tr><td>" . $row['userName'] . "</td><td>" . $row['email'] . "</td></tr>";
}
echo "</table>";
$query1 = "SELECT * FROM users WHERE userName = $userName";
$result1 = mysqli_query($link, $query1);
if(mysqli_num_rows($result1)>=1){
echo "user exists";
}
else {
echo "user doesnt exist";
}
mysqli_close($link);
?>

Answer 1

You have a syntax error in your query that fill the variable $result1 with false. That occurs your error. Try my example below. I just added ' around $userName in your query and an if statement around your mysqli_num_rows function.
$link = mysqli_connect('localhost', 'root', '', 'k3462_top-tree');
$query = "SELECT * FROM users";
$userName = $_GET['userName'];
$result = mysqli_query($link, $query);
echo "<table>";
while($row = mysqli_fetch_array($result)){
echo "<tr><td>" . $row['userName'] . "</td><td>" . $row['email'] . "</td></tr>";
}
echo "</table>";
$query1 = "SELECT * FROM users WHERE userName = '$userName'";
$result1 = mysqli_query($link, $query1);
if( $result1 ) {
if(mysqli_num_rows($result1)>=1){
echo "user exists";
}
else {
echo "user doesnt exist";
}
} else {
echo "query or db error";
}
mysqli_close($link);

Answer 2

$query1 = "SELECT * FROM users WHERE userName = '$userName'";