MySQL `UPDATE` statement with an `IF` condition - php

Question

I'm trying to create a MySQL UPDATE statement with an IF condition.
I would like to update the user's particulars if the email and username are not duplicate or found in database.
I'm stuck with this code:
<?php
include "connection.php";
$user = $_REQUEST['user'];
$em = $_REQUEST['email'];
$id = $_REQUEST['id_user'];
//Check Email in Database
$query = mysqli_query($con,"SELECT username, email from `user` where id_user = '$id'");
$result = mysqli_fetch_object($query);
if (strtolower(trim($query->email)) == strtolower(trim($em))
|| strtolower(trim($user->username)) == strtolower(trim($user))
) {
//next to condition username
} else {
$data_email = mysqli_query($con,"select email from user where em='".$em."'");
$total_email = mysqli_num_rows($data_email);
if($total_email > 0) {
echo "Email Not Available";
} else {
//next to condition username
}
}
//Check Username in Database
$data_us_user = mysqli_query($con,"select username from user where id_user='".$id."'");
$us_user = mysqli_fetch_object($data_us_user);
if (strtolower(trim($us_user->username))==strtolower(trim($user))) {
//next to query update
} else {
$data_username = mysqli_query($con,"select username from user where username='".$em."'");
$total_username = mysqli_num_rows($data_username);
if($total_username > 0) {
echo "Username Not Available";
} else {
//next to query update
}
} else {
//Finally Query Update
mysqli_query($con,"update user set username='".$user."',em='".$em."' where id_user='".$id."' ");
echo "OK";
}

Answer 1

The following PHP script will check for
IF the user's updated email and updated username are the same
IF the user's new email and username is already in use by another user
IF both conditions are not met, the user's details will be updated
PHP code:
<?php
include "connection.php";
$user = $_REQUEST['user'];
$em = $_REQUEST['email'];
$id = $_REQUEST['id_user'];
//Getting user' details in database
$query = mysqli_query($con, "SELECT username, email from `user` where id_user = '$id'");
$result = mysqli_query($query);
//Query to find if email exists
$query2 = mysqli_query($con,"SELECT `email` from `user` WHERE em = '$em'");
$result2 = mysqli_num_rows($query2);
//Query to find if username exists
$query3 = mysqli_query($con,"SELECT `email` from `user` WHERE id_user = '$user");
$result3 = mysqli_num_rows($query3);
while ($row = mysqli_fetch_row($result)){
list($userfromdb, $emfromdb) = $row;
}
if (strtolower(trim($userfromdb)) == strtolower(trim($user))){
//will return true if user's username is the same before updating
echo 'Username cannot be the same!';
} else if(strtolower(trim($emfromdb)) == strtolower(trim($em))) {
//will return true if user's email is the same before updating
echo 'Email cannot be the same!';
} else if($result2 > 0) {
echo "Email Not Available";
} else if($result3 > 0) {
echo "Username Not Available";
} else {
//Finally Query Update
mysqli_query($con, "UPDATE `user` set username = '$user',em = '$em' WHERE id_user = '$id'");
//check if row updated successfully
$result4 = mysqli_affected_rows($con);
if ($result4 > 0) {
echo "Updated details successfully";
} else {
echo "An error occurred while updated details.";
}
}
?>
This should work, thanks!

Answer 2

If specifying column related message is not the concern,
<?php
include "connection.php";
$user = $_REQUEST['user'];
$em = $_REQUEST['email'];
$id = $_REQUEST['id_user'];
$data_us_em = mysqli_query($con,"select count(email) as count from user where id_user='".$id."' OR em='".$em."' OR username='".$em."'");
if($data_us_em)
{
$us_em = mysqli_fetch_assoc($data_us_em);
$count=$us_em['count'];
if($count)
{
echo 'Can not update';
}else
{
mysqli_query($con,"update user set username='".$user."',em='".$em."' where id_user='".$id."' ");
echo "OK";
}
}
?>

Answer 3

$data_user= mysqli_query($con,"select email,username from user where id_user='".$id."'");
$userdetail = mysqli_fetch_object($data_user);
if (strtolower(trim($userdetail->email))==strtolower(trim($em)) || strtolower(trim($userdetail->username))==strtolower(trim($user)))
{
return "error message";
}else{
//your update method here
}