Jump to content

Check if record exists, update quantity if it does or insert new record otherwise


jeffcodedev123
 Share

Recommended Posts

Hello I need some help please!

I have a web page that currently inserts a record containing customerID, productID and quantity into the cart table if a user adds a product to their cart. However, if the user goes back to the shop and re-adds that same product to their cart. The php/mysql creates a new record regardless of what they have in their cart.

Current output in table:

customerID           productID                    quantity

1                            ABC12                            3

1                            ABC12                            1

 

Expected output:

customerID           productID                    quantity

1                            ABC12                            4

 

All help is greatly appreciated. 

<!doctype html>
<html>
    <head>
        <title>Add Item to Cart</title>

        <?php 
        session_start();
        echo $_SESSION["user_id"];

        $user_id = $_SESSION["user_id"];
        
        $stockID = $_POST['stockNo'];
        $quantity = $_POST['quantity'];
    
        
        //connect to database. 
        include 'dbConnect.php';

        
        //create MySQL insert command
        $query1 = "insert into cart (customerID,stockID,quantity) values('$user_id','$stockID','$quantity');
        //execute the MySQL statement
        $result1 = mysqli_query($db,$query1);       
        ?> 

    </head>
    <body>
        <?php include 'navBar.php'; ?>
        <h1>Adding to cart....</h1>
        <br>
            <?php 

              if ($result1){
                   echo "Item has been added to your cart.";
                }
              else {
                    echo "Theres been a problem.  Item was not added to your cart.";
                }
            ?>
    </body>
    <?php //close connection to the database
    mysqli_close();
    ?>
</html>

Edited by jeffcodedev123
error
Link to comment
Share on other sites

Define customer/product as UNIQUE...

CREATE TABLE `cart` (
  `cart_id` int(11) NOT NULL AUTO_INCREMENT,
  `customerID` int(11) DEFAULT NULL,
  `productID` varchar(5) DEFAULT NULL,
  `quantity` int(11) DEFAULT NULL,
  PRIMARY KEY (`cart_id`),
  UNIQUE KEY `UNQ_cart_product` (`customerID`,`productID`)
)

BEFORE

+---------+------------+-----------+----------+
| cart_id | customerID | productID | quantity |
+---------+------------+-----------+----------+
|       1 |          1 | ABC12     |        3 |
|       2 |          1 | DEF23     |        5 |
+---------+------------+-----------+----------+

UPDATE

INSERT INTO cart (customerID, productID, quantity)
VALUES 
(1, 'ABC12', 2),
(1, 'DEF23', 5),
(1, 'GHI34', 10)
ON DUPLICATE KEY UPDATE
    quantity = quantity + VALUES(quantity);

AFTER

+---------+------------+-----------+----------+
| cart_id | customerID | productID | quantity |
+---------+------------+-----------+----------+
|       1 |          1 | ABC12     |        5 |
|       2 |          1 | DEF23     |       10 |
|       3 |          1 | GHI34     |       10 |
+---------+------------+-----------+----------+
Edited by Barand
  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.