sql combine two queries in one and SORT BY

Question

I have a large table and I've built two queries to first query the first 2 columns and then the other columns. My intention obviously to put first 2 columns data on top then append the other columns's data below. Here is the query.

SELECT * FROM (SELECT * FROM mytable WHERE A LIKE 'query%' OR G LIKE 'query%' ORDER BY LENGTH(A) )
UNION ALL
SELECT * FROM (SELECT * FROM mytable WHERE I LIKE 'query' OR J LIKE 'query' LIMIT 15)

This works okay but it is way too slow. Is there any way I can make it faster. Because I feel like I am making unnecessary SELECTS (4). Maybe I can make something like (I saw this suggestion here on Stackoverflow):

SELECT  * 
FROM 
        (
            SELECT *, 1 sortby FROM TABLE_A 
            UNION ALL 
            SELECT *, 2 sortby FROM TABLE_B
        ) dum
ORDER   BY sortby 

But I have no idea how to do it for my case.

Thanks alot.

Answer 1

Yes, you´re right. There is 2 un-needed selects in your query. This would work, but I doubt that it would be any better performance.

SELECT * FROM mytable WHERE A LIKE 'query%' OR G LIKE 'query%' 
UNION ALL
SELECT * FROM mytable WHERE I LIKE 'query' OR J LIKE 'query' LIMIT 15
ORDER BY LENGTH(A)

Answer 2

Have you try this :

Select m1.A,m2.I from (SELECT A FROM mytable m1 WHERE A LIKE 'query%' OR G LIKE 'query%'

ORDER BY LENGTH(A)

 UNION ALL

SELECT I FROM mytable m2 WHERE I LIKE 'query' OR J LIKE 'query' LIMIT 15))
ORDER BY m1.A,m2.I