将多维数组插入MySQL Table文本字段

Question

I'd like to insert a multidimensional array into a MySQL Database field so that it can then easily be read from the database at a later date back into an array. What's the best way to achieve this?

I've tried the following to no avail:

$id    = "MXB-487"
$items = Array(Array("Coffee", "Blend", "500"), Array("Coffee1", "Blend1", "250"));
$items = implode(",", $items);
mysqli_query($con,"INSERT INTO carts (id, items) 
VALUES ($id, $items)");

/*Code that pulls the array from the Database based on id and stores in variable $info*/
restored_mdarray = explode(",", $info);

Answer 1

ID in MySql, is usually unique (I'm pretty sure you specified it that way). So, you can't share the ID for multiple items. Also, imploding will end up with the following query:

INSERT INTO carts (id, items) VALUES(MXB-487, Array, Array)

Because you have a multidimensional array you're trying to implode, it doesn't recursively implode.

What you should do is loop through the objects, and I'm not sure how the relationship here works, but it looks like you need a relation table to connect those items. Consider the following structure:

    Carts:
    +----------+-----------+
    |    ID    |   Name    |
    +----------+-----------+
--<-|  MXB-487 | Blah blah |
|   +----------+-----------+
|
|   Items:
|   +----------+-----------+----------+-----------+
|   | Cart_ID  | Type1     | Type 2   | Amount    |
|   +----------+-----------+----------+-----------+
--->| MXB-487  | Coffee    | Blend    | 500       |
    +----------+-----------+----------+-----------+

And in order to implement that in PHP, you'd do something like this:

<?php
$id = "MXB-487";
$items = array(
    array("Coffee", "Blend", "500"),
    array("Coffee1", "Blend1", "500"),
);

$sql = "INSERT INTO actions (cart_id, type1, type2, amount) VALUES ";

$items_sql = array();
if (count($items)) {
    foreach ($items as $item) {
        $items_sql[] = "('$id', '{$item[0]}', '{$item[1]}', '{$item[2]}')";
    }
}

$sql .= implode(", ", $items_sql);

And then run the query.

It will look like this:

INSERT INTO actions (cart_id, type1, type2, amount) VALUES ('MXB-487', 'Coffee', 'Blend', '500'), ('MXB-487', 'Coffee1', 'Blend1', '500')

Which you can later select as such:

<?php
$id = "MXB-487";

$sql = "SELECT * FROM actions WHERE (cart_id = '$id')";

Though as a side note, I suggest you look at PDO and how to bind values, or at least learn to escape your values in the SQL to prevent future injections.

I speculated the structure of the tables, of course you can modify to your needs.

To connect the tables properly via SQL (to fasten the fetching later on) you can use FOREIGN KEY when you define the table:

CREATE TABLE actions (
    id INT(11) NOT NULL AUTO_INCREMENT,
    cart_id VARCHAR(32) NOT NULL,
    type1 VARCHAR(32) NOT NULL,
    type2 VARCHAR(32) NOT NULL,
    amount INT NOT NULL,

    PRIMARY KEY (id),
    FOREIGN KEY (cart_id) REFERENCES carts(id)
)

Answer 2

Use serialize :

$a = array(array(1,2,3), array(3,4,5));
$b = serialize($a);
# write $b to and later read $b from database
$c = unserialize($b);
$a == $c   # => true