Mysql JOIN：只有在多个连接匹配的行匹配时才会选择

Question

我在想这里的某个人是否可以帮我重述这个，所以我只从works得到结果if works。 id + prod_instruments_id + number全部都在works_instruments？

这是我有：

SELECT 
    `works`.`id`, 
    `composers`.`first_name` 
FROM `works` 
    JOIN `composers` ON `works`.`composers_id` = `composers`.`id` 
    JOIN `works_instruments` ON `works`.`id` = `works_instruments`.`works_id` 
WHERE 
    (true) 
    AND `composers`.`full_name` LIKE '%karl friedrich abel%' 
    AND `works_instruments`.`prod_dd_instruments_id` = 15 
    AND `works_instruments`.`number` >= 1 
    AND `works_instruments`.`prod_dd_instruments_id` = 5 
    AND `works_instruments`.`number` >= 1 
    AND `works`.`work_no` <> '001' AND `works`.`short_title` NOT LIKE '%*Works' 
ORDER BY 
    `composers`.`last_name`, 
    `composers`.`first_name`, 
    `works`.`full_title` 
LIMIT 0,50 

眼下这种不返回任何结果。 但是这并不：

SELECT 
    `works`.`id`, 
    `composers`.`first_name` 
FROM `works` 
    JOIN `composers` ON `works`.`composers_id` = `composers`.`id` 
    JOIN `works_instruments` ON `works`.`id` = `works_instruments`.`works_id` 
WHERE 
    (true) 
    AND `composers`.`full_name` LIKE '%karl friedrich abel%' 
    AND `works_instruments`.`prod_dd_instruments_id` = 15 
    AND `works_instruments`.`number` >= 1 
    AND `works`.`work_no` <> '001' AND `works`.`short_title` NOT LIKE '%*Works' 
ORDER BY 
    `composers`.`last_name`, 
    `composers`.`first_name`, 
    `works`.`full_title` 
LIMIT 0,50 

而且这样做：

SELECT 
    `works`.`id`, 
    `composers`.`first_name` 
FROM `works` 
    JOIN `composers` ON `works`.`composers_id` = `composers`.`id` 
    JOIN `works_instruments` ON `works`.`id` = `works_instruments`.`works_id` 
WHERE 
    (true) 
    AND `composers`.`full_name` LIKE '%karl friedrich abel%' 
    AND `works_instruments`.`prod_dd_instruments_id` = 5 
    AND `works_instruments`.`number` >= 1 
    AND `works`.`work_no` <> '001' AND `works`.`short_title` NOT LIKE '%*Works' 
ORDER BY 
    `composers`.`last_name`, 
    `composers`.`first_name`, 
    `works`.`full_title` 
LIMIT 0,50 

你能帮忙吗？

我也尝试过左，右加盟，但仍然是一个空的结果（我只在这里贴左）：

SELECT 
    `works`.`id`, 
    `composers`.`first_name` 
FROM `works` 
    JOIN `composers` ON `works`.`composers_id` = `composers`.`id` 
    LEFT JOIN `works_instruments` ON `works`.`id` = `works_instruments`.`works_id` 
WHERE 
    (true) 
    AND `composers`.`full_name` LIKE '%karl friedrich abel%' 
    AND `works_instruments`.`prod_dd_instruments_id` = 15 
    AND `works_instruments`.`number` >= 1 
    AND `works_instruments`.`prod_dd_instruments_id` = 5 
    AND `works_instruments`.`number` >= 1 
    AND `works`.`work_no` <> '001' AND `works`.`short_title` NOT LIKE '%*Works' 
ORDER BY 
    `composers`.`last_name`, 
    `composers`.`first_name`, 
    `works`.`full_title` 
LIMIT 0,50 

难道works_instruments没有潮头ID的问题？ 见的works_instruments这里截图： Screenshot

Answer 1

没有数值，其中一个字段可以= 15，= 5在同一时间。相反，你可以通过works.id做“IN（15，5）”，然后计算不同的prod_dd_instruments_id值来查看是否有两个;或者使用不同的标准集合对同一个表进行两个单独的连接。

编辑：有了你在下面给出的附加信息，类似这样的东西可能会更有帮助。

SELECT works.*, composers.* 
, SUM(IF(wi.prod_dd_instruments_id=15, wi.number, 0)) AS count15 
, SUM(IF(wi.prod_dd_instruments_id=5, wi.number, 0)) AS count5 
FROM works 
INNER JOIN `composers` ON `works`.`composers_id` = `composers`.`id` 
LEFT JOIN `works_instruments` AS wi ON `works`.`id` = wi.`works_id` 
WHERE [the other criteria you had] 
GROUP BY works.id 
HAVING count15 > 1 AND count5 > 1 
; 

注意这个查询只适用于 “5 & 15”;虽然（从你的“(true)”我hazarding你部分的代码构建查询在租赁猜测来判断，所以我认为这将不会太困难，使上述多一点的代码灵活。