sort same field from different tables - php

Question

I have somes tables (around 20) with the same structure and I'm trying to sort them with a php script and insert them in a new table with the cheapest price in cheapest1, then cheapest2 for more expensive... and the most expensive in column cheapest20:
table A:
id
name
price
table B:
id
name
price
table X:
id
name
price
tableResult:
id
name
cheapest1
price1
cheapest2
price2
...
cheapestX
priceX
My code so far is:
(SELECT id, price, name FROM tableA WHERE id = $id)
UNION
(SELECT id, price, name FROM tableB WHERE id = $id)
ORDER BY price ASC
I have been looking for different solutions but it takes too long to SELECT for 15000 rows so I guess there is another way to do it.
I haven't looked for the update query yet, I need to fix the select in the first time.
Any suggestion?
EDIT: clarified question, with more tables
EDIT2: solution
I finally got it right. This is the query to select the cheapest:
I select each id and I browse:
(SELECT price AS P1, name, id FROM tableA WHERE id = ?) UNION (SELECT price AS P1, name, id FROM tableB WHERE id = ?) UNION (SELECT price AS P1, name, id FROM tableC WHERE id = ?) ORDER BY P1 ASC
Then I Insert in the new table as glglgl suggested:
('INSERT INTO table (id, name, Position, price) VALUES (?, ?, ?, ?) ');

Answer 1

If you have control over the final structure of the tables: Don't do that. Instead, use only one table and add a field for indicating which purpose it serves.
The target table is not structured well either. Instead, you should use
tableResult:
id
name
cheapestorder
cheapest
price
which makes all easier.
Thus, instead of having one row containing
id=10, name=foo, cheapest1=a, cheapestprice1=10, cheapest2=b, cheapestprice2=13,
you have several rows
id=10, name=foo, cheapestorder=1, cheapest=a, cheapestprice=10
id=10, name=foo, cheapestorder=2, cheapest=b, cheapestprice=13
(This process is called "normalization" in database theory.)
Putting all input tables into one simplifies dcp's query:
SELECT name,
max(mxprice) mxprice,
min(mnprice) mnprice
FROM
(
SELECT name,
max(price) mxprice,
min(price) mnprice
FROM tableABC
GROUP BY NAME, tbltag
) a
GROUP BY NAME
or maybe even just
SELECT name,
max(price) mxprice,
min(price) mnprice
FROM tableABC
GROUP BY NAME
.

Answer 2

I did this on Oracle, but syntax should be very similar for MySQL (the select should work without any changes at all).
CREATE TABLE tableA (NAME VARCHAR2(100), price FLOAT);
CREATE TABLE tableB (NAME VARCHAR2(100), price FLOAT);
INSERT INTO tableA VALUES ('a',14.23);
INSERT INTO tableA VALUES ('b',15.23);
INSERT INTO tableA VALUES ('b',16.23);
INSERT INTO tableB VALUES ('a',12.23);
INSERT INTO tableB VALUES ('a',13.23);
INSERT INTO tableB VALUES ('b',9.23);
SELECT name
, max(mxprice) mxprice
, min(mnprice) mnprice
FROM
(
SELECT name
, max(price) mxprice
, min(price) mnprice
FROM tableA
GROUP BY NAME
UNION ALL
SELECT name
, max(price) mxprice
, min(price) mnprice
FROM tableB
GROUP BY NAME
) a
GROUP BY NAME
Result:
NAME MXPRICE MNPRICE
1 a 14.23 12.23
2 b 16.23 9.23