调整SQL查询。 如何将IN更改为更快的内容

Question

I have a website that is running a query off to Mysql when a search term is entered. I built a sql statement like this

SELECT * FROM catelogue
WHERE `DEPARTMENT` LIKE 'MUSIC'
AND ( `ARTIST` LIKE '%$theValue%' OR `TITLE` LIKE '%$theValue%' OR 
    `CAT NO.` IN 
    (SELECT `TRACKLISTING CAT NO.`
    FROM tracklisting 
    WHERE `ARTIST` LIKE '%$theValue%' OR `TRACK TITLE` LIKE '%$theValue%'))
    ORDER BY `RELEASEDATE` DESC

It worked great on wamp locally when testing. Now I have uploaded the site to my host and the query seems to be crashing or slowing it down that it doesn't even load the page.

I redesigned the query to this

SELECT `ARTIST` , `TITLE` , `CAT NO.` , `FORMAT` , `DEPARTMENT` , `SELL`,`IMAGE PATH` 
        FROM catelogue
WHERE `DEPARTMENT` LIKE 'MUSIC'
AND ( `ARTIST` LIKE '%$theValue%' OR `TITLE` LIKE '%$theValue%') 
    ORDER BY `RELEASEDATE` DESC"

As this stands it works great on my host now but I can't search my tracklisting table. I need to know how to change IN to something that works faster.

The catelogue and tracklisting table are linked by the CAT NO.

Thanks

EDIT

A BIG THANKS TO EVERYONE THAT HELPED

Now onto some bad news. This is the code I'm using now. It doesn't return any errors but it also doesn't return any results either

SELECT c.`ARTIST` , c.`TITLE` , c.`CAT NO.` , c.`FORMAT` , c.`DEPARTMENT` , c.`SELL` 
FROM    catelogue c
LEFT JOIN   tracklisting t
        ON  t.`TRACKLISTING CAT NO.` = c.`CAT NO.`
WHERE   'DEPARTMENT' = 'MUSIC'
        AND ((  c.`ARTIST` LIKE '%$theValue%' OR c.`TITLE` LIKE '%$theValue%')
                OR
                (t.`ARTIST` LIKE '%$theValue%' OR t.`TRACK TITLE` LIKE '%$theValue%'))

The tracklisting table doesn't have all the tracklistings for every entry in the catelogue table. Would that make a difference?

I know in ms access you can setup relationships with tables, but I have been unable to figure out if this can be done in phpmyadmin, do I have to setup a relation between the tables for this to work?

Many Thanks

Answer 1

Well, I don't really do PHP so some of your syntax is a little foreign to me but sql is sql and I've just copied the bits I'm not used to.

This should do what you want:

SELECT  *
FROM    catelogue c
    LEFT JOIN   tracklisting t
        ON  t.`TRACKLISTING CAT NO.` = c.`CAT NO.`
WHERE   `DEPARTMENT` = 'MUSIC'
        AND ((  c.'ARTIST' LIKE '%$theValue%' OR c.'TITLE' LIKE '%$theValue%')
                OR
                (t.`ARTIST` LIKE '%$theValue%' OR t.`TRACK TITLE` LIKE '%$theValue%'))
ORDER BY    `RELEASEDATE` DESC

By the way, the field naming in this database is just terrifying IMHO. It would also probably help if you could do some form of full text indexing so that these "contains" LIKE comparisons don't cause you to do full table scans every time. Just a thought.

Answer 2

You can use join the two tables instead of using in clause:

SELECT 
    C.`ARTIST` , 
    C.`TITLE` , 
    C.`CAT NO.` , 
    C.`FORMAT` , 
    C.`DEPARTMENT` , 
    C.`SELL`, 
    C.`IMAGE PATH` 
FROM catelogue C LEFT JOIN tracklisting T
    ON C.`CAT NO.` = T.`TRACKLISTING CAT NO.`
WHERE 
    C.`DEPARTMENT` = 'MUSIC'
    AND (C.`ARTIST` LIKE C.'%$theValue%' OR C.`TITLE` LIKE '%$theValue%') 
    AND (T.`ARTIST` LIKE T.'%$theValue%' OR T.`TRACK TITLE` LIKE '%$theValue%')
ORDER BY 
    `RELEASEDATE` DESC

Note that I changed first condition from LIKE to = (faster) and consider that performance is affected by availability of indexes and by the structure of your query; for example you can:

• evaluate if you can do likes without the first %
• if so, you can add an indexes on C. ARTIST and C. TITLE and one on T. ARTIST and T. TRACK TITLE
• add an index on C. DEPARTMENT

Answer 3

I didn't tested this query, but I think its a good start. Use LEFT join insted of your structure:

SELECT * FROM catelogue  c
LEFT JOIN  tracklisting  t
ON c.`CAT NO.` = t.`TRACKLISTING CAT NO.`
WHERE c.`DEPARTMENT` LIKE 'MUSIC'
AND ( c.`ARTIST` LIKE '%$theValue%' OR c.`TITLE` LIKE '%$theValue%')
OR (t.`ARTIST` LIKE '%$theValue%' OR t.`TRACK TITLE` LIKE '%$theValue%')
ORDER BY c.`RELEASEDATE` DESC