Chcete-li vytisknout soubor locations.title, pokud je k místu v tabulce „listings“ přiřazen alespoň 1 řádek, použijte:
SELECT loc.title
FROM LOCATIONS loc
WHERE EXISTS(SELECT NULL
FROM LISTING li
WHERE li.location = loc.id)
Použijte:
SELECT x.title,
x.address,
x.distance,
x.info,
x.status
FROM (SELECT loc.title,
loc.address,
( 3959 * acos( cos( radians('".$center_lat."') ) * cos( radians( latitude ) ) * cos( radians( longitude ) - radians('".$center_lng."') ) + sin( radians('".$center_lat."') ) * sin( radians( latitude ) ) ) ) AS distance,
li.*,
CASE
WHEN @location = loc.id THEN @rownum := @rownum + 1
ELSE @rownum := 1
END AS rank,
@location := loc.id
FROM LOCATIONS loc
LEFT JOIN LISTINGS li ON li.location = loc.id
JOIN (SELECT @rownum := 0, @location := -1) r
ORDER BY loc.id, RAND()) x
WHERE x.rank = 1
ORDER BY x.distance
Pomocí MySQL 5.1.49-community jsem úspěšně vykreslil požadované výsledky pomocí výše uvedeného dotazu.
Nejsem schopen reprodukovat duplicitní řádek OP pomocí:
VYTVOŘTE TABULKY
CREATE TABLE `locations` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`title` varchar(45) DEFAULT NULL,
`address_street` varchar(45) DEFAULT NULL,
`address_city` varchar(45) DEFAULT NULL,
`address_state` varchar(45) DEFAULT NULL,
`address_zip` varchar(45) DEFAULT NULL,
`latitude` decimal(10,6) DEFAULT NULL,
`longitude` decimal(10,6) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=latin1$$
CREATE TABLE `listings` (
`id` int(11) NOT NULL,
`token` varchar(4) DEFAULT NULL,
`location` varchar(45) DEFAULT NULL,
`info` varchar(45) DEFAULT NULL,
`status` varchar(45) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1$$
INSERT příkazy:
INSERT INTO `locations`
VALUES (1,'John\'s Ice Cream','1701 S Martin Luther King Jr Blvd','Lansing','MI','48910','42.714672','-84.567139'),
(2,'7 Eleven','3500 Okemos Rd','Okemos','MI','48864','42.683331','-84.431709'),
(3,'Kurt\'s Pizza','213 Ann St.','East Lansing','MI','48823','42.736053','-84.481636'),
(4,'Walmart','16275 National Pkwy','Lansing','MI','48906','42.780350','-84.637238'),
(5,'Alex\'s Hot dog Shop','8505 Delta Market Dr','Lansing','MI','48917','42.739830','-84.677330');
INSERT INTO `listings`
VALUES (19,'39c4','1','5 gallons for $8','active'),
(21,'89dF','4','2 mens shirts for $2','active'),
(22,'67oP','1','Ice cream cones for $1','active'),
(23,'5tG8','2','Large soft drinks only $0.99!','active');