This basically is a pivot table.
A nice tutorial on how to achieve this can be found here: http://www.artfulsoftware.com/infotree/qrytip.php?id=78
I advise reading this post and adapt this solution to your needs.
After the link above is currently not available any longer I feel obliged to provide some additional information for all of you searching for mysql pivot answers in here. It really had a vast amount of information, and I won’t put everything from there in here (even more since I just don’t want to copy their vast knowledge), but I’ll give some advice on how to deal with pivot tables the sql way generally with the example from peku who asked the question in the first place.
Maybe the link comes back soon, I’ll keep an eye out for it.
The spreadsheet way…
Many people just use a tool like MSExcel, OpenOffice or other spreadsheet-tools for this purpose. This is a valid solution, just copy the data over there and use the tools the GUI offer to solve this.
But… this wasn’t the question, and it might even lead to some disadvantages, like how to get the data into the spreadsheet, problematic scaling and so on.
The SQL way…
Given his table looks something like this:
CREATE TABLE `test_pivot` ( `pid` bigint(20) NOT NULL AUTO_INCREMENT, `company_name` varchar(32) DEFAULT NULL, `action` varchar(16) DEFAULT NULL, `pagecount` bigint(20) DEFAULT NULL, PRIMARY KEY (`pid`) ) ENGINE=MyISAM;
Now look into his/her desired table:
company_name EMAIL PRINT 1 pages PRINT 2 pages PRINT 3 pages ------------------------------------------------------------- CompanyA 0 0 1 3 CompanyB 1 1 2 0
The rows (
PRINT x pages) resemble conditions. The main grouping is by
In order to set up the conditions this rather shouts for using the
CASE-statement. In order to group by something, well, use …
The basic SQL providing this pivot can look something like this:
SELECT P.`company_name`, COUNT( CASE WHEN P.`action`='EMAIL' THEN 1 ELSE NULL END ) AS 'EMAIL', COUNT( CASE WHEN P.`action`='PRINT' AND P.`pagecount` = '1' THEN P.`pagecount` ELSE NULL END ) AS 'PRINT 1 pages', COUNT( CASE WHEN P.`action`='PRINT' AND P.`pagecount` = '2' THEN P.`pagecount` ELSE NULL END ) AS 'PRINT 2 pages', COUNT( CASE WHEN P.`action`='PRINT' AND P.`pagecount` = '3' THEN P.`pagecount` ELSE NULL END ) AS 'PRINT 3 pages' FROM test_pivot P GROUP BY P.`company_name`;
This should provide the desired result very fast. The major downside for this approach, the more rows you want in your pivot table, the more conditions you need to define in your SQL statement.
This can be dealt with, too, therefore people tend to use prepared statements, routines, counters and such.
Some additional links about this topic: