mysqli_num_rows not working in MySQLi with PHP - php

Question

I would like to check if there already exists a record before inserting a new one. But it doesn't work so far, here is the script:
<?php
session_start();
$uname = $_SESSION['username'];
$friend = $_GET["newfriend"];
$db = new mysqli("localhost", "...", "....", "...");
if($db->connect_errno > 0){
die("Unable to connect to database: " . $db->connect_error);
}
$checkexist = $db->query("SELECT * FROM friends WHERE (username_own='$uname', username='$friend')");
//create a prepared statement
$stmt = $db->prepare("INSERT INTO friends (`username_own`, `username`) VALUES (?,?)");
//bind the username and message
$stmt->bind_param('ss', $uname, $friend);
if ($checkexist->mysqli_num_rows == 0) {
//run the query to insert the row
$stmt->execute();
}

Answer 1

Try something like this:
<?php
/* Check if user exists */
$query = "SELECT count(1) FROM friends WHERE username_own=? AND username=?";
if($stmt = $db->prepare($query)){
$stmt->bind_param('ss', $uname, $friend);
$stmt->execute();
$stmt->bind_result($count_rows);
$stmt->fetch();
$stmt->close();
}else die("Failed to prepare");
/* If user doesn't exists, insert */
if($count_row == 0){
$query = "INSERT INTO friends (`username_own`, `username`) VALUES (?,?)";
if($stmt = $db->prepare($query)){
$stmt->bind_param('ss', $uname, $friend);
$stmt->execute();
$stmt->close();
}else die("Failed to prepare!");
}

Answer 2

Try this:
//create a prepared statement
$stmt = $db->prepare("INSERT INTO friends (`username_own`, `username`) VALUES (?,?)");
//bind the username and message
$stmt->bind_param('ss', $uname, $friend);
if ($checkexist->mysqli_num_rows == 0 || $checkexist->mysqli_num_rows <> 0) {
//run the query to insert the row
$stmt->execute();
}

Answer 3

$checkexist->mysqli_num_rows is wrong. It's just
$checkexist->num_rows
or you can use
mysqli_num_rows($checkexist)
Hope this helps.

Answer 4

Replace most of your code with a simple INSERT IGNORE ... or INSERT ... ON DUPLICATE KEY UPDATE ....
The latter lets you change columns if the record already exists (based on any PRIMARY or UNIQUE key(s)).