How to Check and Repair MySQL The mysql extension is deprecated and will be removed

STEP 1:old way of coding that gives Deprecated Errors:

if(isset($_POST['add_brand'])){

$new_brand = $_POST['new_brand'];

$insert_brand = "insert into brands (brand_title) values ('$new_brand')";

$run_brand = mysql_query($insert_brand); 

if($run_brand){

echo "<script>alert('New Brand has been inserted!')</script>";
echo "<script>window.open('index.php?view_brands','_self')</script>";
}
}

STEP 2: New way of coding and resolving any Deprecated or Missing parameters in codes.

if(isset($_POST['add_brand'])){

$new_brand = $_POST['new_brand'];

$insert_brand = "insert into brands (brand_title) values ('$new_brand')";

$run_brand = mysqli_query($con, $insert_brand);

if($run_brand){

echo "<script>alert('New Brand has been inserted!')</script>";
echo "<script>window.open('index.php?view_brands','_self')</script>";
}
}

NOTE: $con should be your DB connection variables.  $con. in connect.php