# tabella sessioni
CREATE TABLE sessions(
sess_key varchar(32) NOT NULL default '',
sess_ip tinytext NOT NULL,
sess_agent tinytext NOT NULL,
sess_time int(10) unsigned NOT NULL default '0',
sess_uid mediumint(8) unsigned NOT NULL default '0',
PRIMARY KEY (sess_key)
)ENGINE=MyISAM;

INSERT INTO sessionsVALUES ('12345678901234567890123456789012', '127.0.0.1', 'Firefox', '1234567890', 1);

# tabella utenti
CREATE TABLE users(
user_id mediumint(8) unsigned NOT NULL auto_increment,
PRIMARY KEY (user_id)
)ENGINE=MyISAM;

INSERT INTO users VALUES (1);

SELECT s.*, u.* FROM sessions AS s INNER JOIN users AS u ON (u.user_id = s.sess_uid) WHERE s.sess_key = '12345678901234567890123456789012' AND s.sess_ip = '127.0.0.1' AND s.sess_agent = 'Firefox' LIMIT 1

// o in alternativa

SELECT s.*, u.* FROM sessions AS s, users AS u WHERE s.sess_key = '12345678901234567890123456789012' AND s.sess_ip = '127.0.0.1' AND s.sess_agent = 'Firefox' u.user_id = s.sess_uid LIMIT 1