連接表以獲取另一列的出現次數

Question

我有2張桌子。 一個稱為subscriptions ，另一個稱為service_sushi_service 。 我正在嘗試獲取所有具有兩個以上不同service_id的電話。 例如。

phone: 12345 service id: 12 
phone: 12345 service id: 12 
phone: 12345 service id: 8
phone: 12345 service id: 8
phone: 12345 service id: 13
phone: 22222 service id: 13
phone: 22333 service id: 3

我需要將其輸出為phone = 12345，出現次數= 3

這就是我到目前為止所得到的：而且我不知道如何進一步。

SELECT 
    `sub`.`phone` AS `phone`
FROM 
    `subscriptions` AS `sub`
LEFT JOIN `service_sushi_service` `sushi_service` ON `sushi_service`.`sushi_service_id` = `sub`.`sushi_service_id`
WHERE 
    date(`sub`.`added`) >= '2013-01-01'
GROUP BY `sub`.`phone`

Answer 1

SELECT 
    `sub`.`phone` AS `phone`,
    COUNT(`sushi_service`.`sushi_service_id`) as occurences        
FROM 
    `subscriptions` AS `sub`
LEFT JOIN `service_sushi_service` `sushi_service` ON `sushi_service`.`sushi_service_id` = `sub`.`sushi_service_id`
WHERE 
    date(`sub`.`added`) >= '2013-01-01'
GROUP BY `sub`.`phone`
HAVING occurences > 2

編輯： 應該指出，HAVING似乎只是MySQL的一種東西 。 以為我會將其發布以供您參考-http://dev.mysql.com/doc/refman/5.0/en/group-by-extensions.html

Answer 2

我在這段代碼中看到兩件事：

1. 您為什么要進行LEFT JOIN ？ 我說你需要一個直的INNER JOIN 。

2. 您可以使用count(distinct field_name)來獲取相應的值。

因此，SQL可能如下所示：

SELECT 
    `sub`.`phone` AS `phone`,
     count(distinct `sushi_service`.`sushi_service_id`) as `occurrences`
FROM 
    `subscriptions` AS `sub`
JOIN `service_sushi_service` `sushi_service` ON `sushi_service`.`sushi_service_id` = `sub`.`sushi_service_id`
WHERE 
    date(`sub`.`added`) >= '2013-01-01'
GROUP BY `sub`.`phone`
HAVING `occurrences` > 2

Answer 3

完全不需要加入

select s1.phone, count(s1.*) from 
    (select unique phone, sushi_service_id from subscriptions) s1
group by s1.phone having count(s1.*) > 2