MySQL divide rows an show result on new row - php

Question

I am having difficulties with an MySQL query.
The database looks like this:
Name Unit Int
---------------------
A1 Kilo 20
A1 Price 5
A2 Kilo 15
A2 Price 3
Here is what I'm trying to do:
| Name | Unit | int |
| A1 | Kilo | 20 |
| A1 | Price | 5 |
| A1 | K/P | 4 |
| A2 | Kilo | 15 |
| A2 | Price | 3 |
| A2 | K/P | 5 |
As you can see, I want to insert a new row for every A1 and A2 with a result of Kilo divided by Price.
Is this even possible to do?
If so, could anyone point me in the right direction? I am pretty lost here, and have tried to sweep the internet the last many days, whitout result. I have tried far more ideas than I wish to bore you with.

Answer 1

You could do something like this in your SELECT to calculate it on-the-fly with the latest available data (thus preventing hard-storing something that could later become outdated if the Price/Kilo were to change):
SELECT `kilo`.`name`, (`kilo`.`int` / `price`.`int`) AS 'K/P' FROM `stuff` AS `kilo`
LEFT JOIN `stuff` AS `price` ON (`kilo`.`name` = `price`.`name`)
WHERE `kilo`.`unit`='Kilo' AND `price`.`unit`='Price';
This would return:
+------------+
| name | K/P |
|------------|
| A1 | 4 |
| A2 | 5 |
+------------+
And if you'd really want to insert it into your database you could INSERT ... SELECT the above. Like so:
INSERT INTO `stuff` (`name`, `unit`, `int`)
SELECT `kilo`.`name`, 'K/P', (`kilo`.`int` / `price`.`int`) FROM `stuff` AS `kilo`
LEFT JOIN `stuff` AS `price` ON (`kilo`.`name` = `price`.`name`)
WHERE `kilo`.`unit`='Kilo' AND `price`.`unit`='Price';
See the full SQL Fiddle example here.

Answer 2

You can get all results with
SELECT * FROM (
(SELECT * FROM your_table_name)
UNION
(SELECT r1.Name as Name, 'K/P', r1.Int/r2.Int
FROM your_table_name r1, your_table_name r2
WHERE r1.Name=r2.Name AND r1.Unit='Kilo' AND r2.Unit='Price'
)
) AS derived_table
ORDER BY Name, FIELD(Unit,'Kilo','Price','K/P');