php - MySQL:连接两个表，随机选择一行

Question

首先，我创建了一个屏幕截图，以解释我拥有的内容以及我正在尝试创建的内容。更容易理解。

请在此处查看截屏:http://www.youtube.com/v/lZf3S3EGHDw?fs=1&hl=en_US&rel=0&hd=1

表格:

CREATE TABLE `locations` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `title` varchar(45) DEFAULT NULL,
  `latitude` decimal(10,6) DEFAULT NULL,
  `longitude` decimal(10,6) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

INSERT INTO `locations` (`id`,`title`,`latitude`,`longitude`)
VALUES
    (1,'Randall Automotive Car Repair',42.729642,-84.515524),
    (2,'Belle Tire',42.662458,-84.538177),
    (3,'Better Buy Muffler & Breaks',42.740845,-84.589541),
    (4,'Kwik Car Wash',42.721221,-84.545926);


CREATE TABLE `listings` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `token` varchar(4) DEFAULT NULL,
  `location` varchar(45) DEFAULT NULL,
  `info` varchar(70) DEFAULT NULL,
  `status` varchar(45) DEFAULT NULL,
  `auto_inactive` varchar(10) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;


INSERT INTO `listings` (`id`,`token`,`location`,`info`,`status`,`auto_inactive`)
VALUES
    (35,'4uaJ','1','All employees are NSA certified.','active','0'),
    (36,'RdcX','1','Family Owned and Operated','active','0'),
    (37,'WuaZ','1','Also repair Small engines','active','0'),
    (38,'2jxD','2','Open on the weekends.','active','0'),
    (39,'Xsu4','2','Two locations in this town.','active','0'),
    (40,'p9cB','2','Advertise on Tiger\'s Baseball','active','0'),
    (41,'mYa3','2','Started right here in Michigan','active','0'),
    (42,'Q8g5','3','Building built in 1997','active','0'),
    (43,'l734','3','Great ratings from BBB','active','0'),
    (44,'7cLY','4','Open in the Winter','active','0'),
    (45,'gtlU','4','Largest car wash in town','active','0'),
    (46,'fEjK','4','Owned and Operated by John Smith','active','1285614174'),
    (47,'dRcu','4','Opened in 1987','inactive','0');



<?php

include_once('include.php'); // Calls the Mysql Database`
ini_set('date.timezone', 'America/Detroit');


$user_latitude = 42.7160084;
$user_longitude = -84.5615018;


$sql =  mysqli_query($mysqli, "SELECT 
                                        loc.id, 
                                        loc.title, 
                                        ( 3959 * acos( cos( radians('".$user_latitude."') ) * cos( radians( latitude ) ) * cos( radians( longitude ) - radians('".$user_longitude."') ) + sin( radians('".$user_latitude."') ) * sin( radians( latitude ) ) ) ) AS distance

                                FROM 
                                        locations loc 

                                WHERE EXISTS(SELECT NULL FROM listings li
                                        WHERE li.location = loc.id 
                                        AND li.status = 'active' 
                                        AND (li.auto_inactive > '".time()."' OR li.auto_inactive = '0')) 

                                ORDER BY distance");


while($locations = mysqli_fetch_array($sql)) {

        $listings = mysqli_fetch_array(mysqli_query($mysqli, "SELECT listings.token, listings.info FROM listings WHERE (listings.location = '".$locations['id']."') AND listings.status = 'active' AND (listings.auto_inactive > '".time()."' OR listings.auto_inactive = '0') ORDER BY RAND()"));


        echo '<a href="listing.php?id='.$listings['token'].'"><h2>'.$locations['title'].'</h2></a>';

        echo '<h5>Distance: '.sprintf ('%.2f', $locations['distance']).' mi</h5>';
        echo '<p>'.$listings['info'].'</p>';
        echo '<hr/>';
}

?>

如果您需要任何澄清，请告诉我。谢谢!

Answer 1

这个有效:

SELECT t1.title, t2.token, t2.info
    FROM
        (SELECT loc.id AS id, loc.title AS title,( 3959 * acos( cos( radians('".$user_latitude."') ) * cos( radians( latitude ) ) * cos( radians( longitude ) - radians('".$user_longitude."') ) + sin( radians('".$user_latitude."') ) * sin( radians( latitude ) ) ) ) AS distance
            FROM locations loc
            WHERE EXISTS(SELECT NULL FROM listings li
                    WHERE li.location = loc.id
                        AND li.status = 'active'
                        AND (li.auto_inactive > UNIX_TIMESTAMP() OR li.auto_inactive = '0'))
        ) t1
    JOIN
        (SELECT DISTINCT(listings.location) AS location, listings.token AS token, listings.info AS info
            FROM listings
            WHERE listings.status = 'active'
                AND (listings.auto_inactive > UNIX_TIMESTAMP() OR listings.auto_inactive = '0')
            ORDER BY RAND()
        ) t2
    ON t1.id=t2.location
        GROUP BY t2.location
        ORDER BY t2.location ASC;

我还建议更改 listings 表，使 location、status 和 auto_inactive 列类型为 int - 对它们使用 varchar 毫无意义。