MySQLi Repeat Row Depending on Column Quantity Value

Question

I have created a simple SQL statement to display which products customers have purchased from a woo commerce store.

This is working great but i'm struggling to find a SQL function that repeats rows based on a value, maybe one doesn't exist and PHP is required, any help would be great.

Thanks

CURRENT VIEW    


ORDER ID.  |   PRODUCT NAME.   | QTY
-------------------------------------
   123     |       APPLE       |  3
   124     |       ORANGE      |  2
   125     |       PEAR        |  1

DESIRED VIEW


ORDER ID.  |   PRODUCT NAME.   | QTY
-------------------------------------
   123     |       APPLE       |  3
   123     |       APPLE       |  3
   123     |       APPLE       |  3
   124     |       ORANGE      |  2
   124     |       ORANGE      |  2
   125     |       PEAR        |  1

CODE

<?php

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
 die("Connection failed: " . $conn->connect_error);
}

$sql = "SELECT wppc_wc_customer_lookup.customer_id, wppc_wc_customer_lookup.first_name, 
wppc_wc_customer_lookup.last_name, wppc_wc_customer_lookup.email, 
wppc_wc_order_stats.customer_id, wppc_wc_order_stats.total_sales, 
wppc_wc_order_stats.order_id, wppc_wc_order_stats.date_created, wppc_wc_order_stats.status, 
wppc_woocommerce_order_items.order_id, wppc_woocommerce_order_items.order_item_name, 
wppc_woocommerce_order_items.order_item_id, wppc_woocommerce_order_itemmeta.order_item_id, 
wppc_woocommerce_order_itemmeta.meta_id, wppc_woocommerce_order_itemmeta.meta_key, 
wppc_woocommerce_order_itemmeta.meta_value FROM wppc_wc_customer_lookup

LEFT JOIN wppc_wc_order_stats ON wppc_wc_customer_lookup.customer_id = 
wppc_wc_order_stats.customer_id

LEFT JOIN wppc_woocommerce_order_items ON wppc_wc_order_stats.order_id = 
wppc_woocommerce_order_items.order_id

LEFT JOIN wppc_woocommerce_order_itemmeta ON wppc_woocommerce_order_items.order_item_id = 
wppc_woocommerce_order_itemmeta.order_item_id


WHERE wppc_woocommerce_order_itemmeta.meta_key = '_qty' AND 
wppc_woocommerce_order_items.order_item_name = 'Product Name' AND 
wppc_wc_order_stats.status = 'wc-completed'


ORDER BY wppc_wc_order_stats.date_created DESC";

$result = $conn->query($sql);

echo "<table border=\"1\"><tr>";
echo "<tr><th>Order ID</hr><th>First Name</hr><th>Last Name</hr><th>Email</hr><th>Total</hr> 
<th>Order Date</hr><th>Product Name</hr><th>Quantity</hr>";

if ($result->num_rows > 0) {

// output data of each row
while($row = $result->fetch_assoc()) {

echo "<tr><td>".$row["order_id"]. " </td><td> " .$row["first_name"] . " </td><td> " . 
$row["last_name"] . " </td> <td> " . $row["email"] . " </td><td> &pound".$row["total_sales"] 
. " </td> <td>".$row["date_created"] . " </td> <td> ".$row["order_item_name"] . " </td> <td> 
".$row["meta_value"] . " </td></tr> ";

}

} else {
echo "0 results";
}

echo "</table>";

$conn->close();
?>

This is working great but i'm struggling to find a SQL function that repeats rows based on a value, maybe one doesn't exist and PHP is required, any help would be great.

Answer 1

the idea is to make multiple select queries with different where clauses;

for instance in this case we need query like this:

SELECT * FROM table WHERE QTY > 0
UNION ALL
(SELECT * FROM table WHERE QTY > 1)
UNION ALL
(SELECT * FROM table WHERE QTY > 2)
ORDER BY `ORDER ID`

so we can create mysql procedure to generate such query depending on maximum qty like so

CREATE PROCEDURE GetAllProducts()
BEGIN
    select max(QTY) - 1 into @maxQty from table;
    set @resQry = 'SELECT * FROM table WHERE QTY > 0';
    set @i = 0;

    label1:
    LOOP
        IF @i = @maxQty THEN
            leave label1;
        END IF;
        SET @i = @i + 1;
        SET @resQry = CONCAT(@resQry, ' UNION ALL (SELECT * FROM table WHERE QTY > ', @i, ')');
    END LOOP label1;
    SET @resQry = CONCAT(@resQry, ' ORDER BY `ORDER ID`');
    PREPARE stmt FROM @resQry;
    EXECUTE stmt;
END;

and then you can call this procedure

CALL GetAllProducts();

Answer 2

If you are running MySQL 8.0, you can do this with a recursive query. Starting from your existing query, that would be:

with recursive 
    data  as ( <... your query goes here ...> ),
    rcte as (
        select order_id, product_name, qty, 1 rn from data
        union all 
        select order_id, product_name, qty, rn + 1 from rcte where rn < qty
)
select order_id, product_name, qty from rcte

In earlier versions, you could use a table of numbers. Here is an example that would quantities up to 3:

select d.*
from ( <... your query goes here ...> ) d
inner join (select 1 qty union all select 2 union all select 3) n 
    on n.qty <= d.qty

You can expand the subquery with more union all s to handle greater quantities.