Question

I need a SQL Query that shows me all polls a user (uid) has not voted yet.

Example:

• There are pid 1, 2 and 3
• uid 1 voted on poll 1 and 3

So I need the query that shows me the pid 2 he didnt vote yet.

This are the 2 tables:

CREATE TABLE IF NOT EXISTS `poll` (
`pid` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(200) NOT NULL,
`description` text NOT NULL,
`deadline` datetime NOT NULL,
PRIMARY KEY (`pid`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=4 ;


CREATE TABLE IF NOT EXISTS `votes` (
`vid` int(11) NOT NULL AUTO_INCREMENT,
`pid` int(11) NOT NULL,
`uid` varchar(20) NOT NULL,
`tid` int(11) NOT NULL,
`votes` int(11) NOT NULL DEFAULT '1',
PRIMARY KEY (`vid`),
KEY `pcid` (`pid`,`uid`),
KEY `uid` (`uid`),
KEY `tid` (`tid`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=19 ;

//edit this should make it more clear

Constraints for table votes

ALTER TABLE `votes`
ADD CONSTRAINT `votes_ibfk_3` FOREIGN KEY (`pid`) REFERENCES `poll` (`pid`) ON DELETE CASCADE ON UPDATE CASCADE,
ADD CONSTRAINT `votes_ibfk_4` FOREIGN KEY (`uid`) REFERENCES `user` (`uid`) ON DELETE CASCADE ON UPDATE CASCADE,
ADD CONSTRAINT `votes_ibfk_5` FOREIGN KEY (`tid`) REFERENCES `teams` (`tid`) ON DELETE CASCADE ON UPDATE CASCADE;

Can smbdy please help me. I guess it is a join with a WHERE and NOT LIKE but I just dont get it.

Merci!

Answer 1

okay so this is my first answer. There might me more possibilities, but this should work.

SELECT * FROM Poll WHERE pid NOT IN (SELECT pid FROM votes WHERE uid = 1);

I’m not 100% sure this will work as I don’t know the database type from which you’re trying to retrieve your data.