MySQL query - joining two tables producing duplicate results - php

Question

I'm running the following MySQL query in PHP.
"SELECT *
FROM `challenges`,`verifications`
WHERE (`challenges`.`user_id`='".$this->record['id']."' OR `challenges`.`opponent_id`='".$this->record['id']."')
AND `challenges`.`is_verified`='0'
AND (`challenges`.`status`='in-progress' OR `challenges`.`status`='pending')
AND
(
(`verifications`.`user_id`='".$this->record['id']."' OR `verifications`.`opponent_id`='".$this->record['id']."')
AND (`verifications`.`user_verified`!=NULL AND `verifications`.`opponent_verified`=NULL)
)
LIMIT 100";
This query is returning duplicate records for some reason. If anyone has any insights, I would greatly appreciate it.
Here is the structure for the two tables (challenges and verifications):
Challenges Table:
CREATE TABLE `challenges` (
`id` int(11) NOT NULL auto_increment,
`wager` int(11) NOT NULL,
`type` varchar(255) NOT NULL,
`user_id` int(11) NOT NULL,
`opponent_id` int(11) NOT NULL,
`start_date` date NOT NULL,
`date_created` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP,
`start_time` time NOT NULL,
`is_verified` tinyint(1) NOT NULL default '0',
`status` varchar(255) NOT NULL default 'pending',
`winner_id` int(11) default NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=0 ;
Verifications Table:
CREATE TABLE `verify` (
`id` int(11) NOT NULL auto_increment,
`user_id` int(11) NOT NULL,
`opponent_id` int(11) NOT NULL,
`challenge_id` int(11) NOT NULL,
`user_verified` int(11) default NULL,
`opponent_verified` int(11) default NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `challenge_id` (`challenge_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=0;
Thanks for your help, and if you need any more info please let me know.

Answer 1

You have to add condition:
challenges.id = verify.challenge_id
to where clause as below
"SELECT *
FROM `challenges`,`verifications`
WHERE `challenges`.`id` = `verify`.`challenge_id`
AND (`challenges`.`user_id`='".$this->record['id']."'
OR `challenges`.`opponent_id`='".$this->record['id']."')
AND `challenges`.`is_verified`='0'
AND (`challenges`.`status`='in-progress' OR `challenges`.`status`='pending')
AND ( (`verifications`.`user_id`='".$this->record['id']."'
OR `verifications`.`opponent_id`='".$this->record['id']."')
AND (`verifications`.`user_verified`!=NULL
AND `verifications`.`opponent_verified`=NULL)
)
LIMIT 100";
or using ANSI-92
"SELECT *
FROM `challenges` as `challenges`
JOIN `verifications` as `verifications` on `challenges`.`id` = `verify`.`challenge_id`
WHERE (`challenges`.`user_id`='".$this->record['id']."' OR `challenges`.`opponent_id`='".$this->record['id']."')
AND `challenges`.`is_verified`='0'
AND (`challenges`.`status`='in-progress' OR `challenges`.`status`='pending')
AND
(
(`verifications`.`user_id`='".$this->record['id']."' OR `verifications`.`opponent_id`='".$this->record['id']."')
AND (`verifications`.`user_verified`!=NULL AND `verifications`.`opponent_verified`=NULL)
)
LIMIT 100";