如何继续在PHP中增加价值

<?php
    $con=mysqli_connect("localhost","xx","xx","xx");

$con2=mysqli_connect("localhost","xx","xx","xx");

    $name = $_POST["name"];
    $state = $_POST["state"];
    $feedback = $_POST["feedback"];
    //$ad_id= $_POST["ad_id"];
    $rate= $_POST["rate"];

    $ad_rating = $_POST["ad_rating"];
    $ad_id= $_POST["ad_id"];

    $statement = mysqli_prepare($con, "INSERT INTO user_feedback(name, state, feedback, ad_id, rate) VALUES (?,?,?,?,?)");

    $statement2 = mysqli_prepare($con, "UPDATE post_ads SET ad_rating= $ad_rating + $ad_rating WHERE ad_id= ?");

        mysqli_stmt_bind_param($statement, "sssss", $name, $state, $feedback, $ad_id, $rate);

    mysqli_stmt_bind_param($statement2, "ss", $ad_rating, $ad_id);

        mysqli_stmt_execute($statement);

        mysqli_stmt_close($statement);

        mysqli_stmt_execute($statement2);

        mysqli_stmt_close($statement2);

        mysqli_close($con);


?>

Database example

I currently doing a mobile apps and need to parse data into database and here is my php code.

i currently have ad_rating attribute inside my database table and i have attach the image link here.

My problem is that every time i update new value of ad_rating, how should i add it with previous one? Example ad_rating = 4, so when i try to do a new request by sending ad_rating = 3, i want to add it with my previous ad_rating value which is 4, so the value inside ad_rating become 7.

You can use an insert statement:

insert into post_ads
(ad_id, ad_rating)
values (?,?)
on duplicate key update ad_rating=values(ad_rating)+ad_rating;

You're almost there, just need to...

1. Remove the $ from the first ad_rating being added so it represents the current value in the database, rather than a PHP var.
2. Use a ? to represent the parameter you bind 2 lines later.

Like so:

$statement2 = mysqli_prepare($con, "UPDATE post_ads SET ad_rating = ad_rating + ? WHERE ad_id = ?");