Daevid Vincent wrote: >If I have a table with a primary key like this: > >CREATE TABLE `answers` ( >`qid` INT UNSIGNED NOT NULL , >`userid` INT UNSIGNED NOT NULL , >`groupid` INT UNSIGNED NOT NULL , >`comments` TEXT NOT NULL , > PRIMARY ( `qid` , `userid` , `groupid` ) >); > >But I will also be searching in various pages, for all 'answers' from a >certain userid or say that belong to a certain groupid, do I still need to >create separate INDEXes for those fields, or is it enough to have them in >that combination PRIMARY key? > > You need to have separate indexes. If you have a composite index and just have one field in the where clause ( or in a join ), the index won't be used at all. It says this somewhere in the documentation.
Also, while the above table definition is legal, I would have an auto_increment primary key, and then if you want to make ( `qid` , `userid` , `groupid` ) unique, define a unique index across them. -- Daniel Kasak IT Developer NUS Consulting Group Level 5, 77 Pacific Highway North Sydney, NSW, Australia 2060 T: (+61) 2 9922-7676 / F: (+61) 2 9922 7989 email: [EMAIL PROTECTED] website: http://www.nusconsulting.com.au -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
