甲骨文返回行只有当所有的连接条件匹配

Question

http://sqlfiddle.com/#!4/bab93d

参见SQL小提琴例子......我有客户，标签和映射表。我试图通过标签实现客户搜索，并且它必须是AND搜索。查询被传递一个标签标识符列表（任何数字），并且它只能返回具有所有标签的客户。

在这个例子中，我使用了一个IN运算符，但是这对应于OR搜索并且不能解决我的问题。查询看起来应该是什么样的AND搜索？

select 
    * 
from 
    customer c 
    inner join customer_tag ct on ct.customer_id = c.customer_id 
where 
    ct.tag_id in (1, 2); 

这两者都返回客户，但只有第一个客户被打上标签1和2

Answer 1

你可以使用相关子查询来获取所有客户的名单：

SELECT * 
FROM customer c 
WHERE c.customer_ID IN 
(
    SELECT customer_id 
    FROM customer_tag ct 
    WHERE ct.customer_id = c.customer_id 
     AND ct.tag_id IN (1,2) 
    GROUP BY customer_id 
    HAVING COUNT(DISTINCT tag_id) = 2 
); 

LiveDemo

很容易扩展ju ST：

WHERE ct_tag IN (1,2,3) 
... 
HAVING COUNT(DISTINCT tag_id) = 3 

Answer 2

你可以做类似

SELECT * 
FROM customer c 
WHERE 
    2 = (SELECT COUNT(DISTINCT ct.tag_id) 
     FROM customer_tag ct 
     WHERE ct.customer_id = c.customer_id AND ct.tag_id IN (1, 2)); 

的2 = ...部分应根据您要搜索的标签数量进行调整。

---

替代的解决方案 - 相关子查询可以有表现不佳，所以你可以在表中加入这样

SELECT c.* 
FROM customer c 
    INNER JOIN (
    SELECT ct.customer_id 
    FROM customer_tag ct 
    WHERE ct.tag_id IN (1, 2) 
    GROUP BY ct.customer_id 
    HAVING COUNT(DISTINCT ct.tag_id) = 2 
) ct ON ct.customer_id = c.customer_id; 

Answer 3

JOIN版本：

SELECT c.* 
FROM customer c 
JOIN (SELECT customer_id 
     FROM customer_tag 
     WHERE tag_id IN (1,2) 
     GROUP BY customer_id 
     HAVING MAX(tag_id) <> MIN(tag_id)) ct ON c.customer_id = ct.customer_id 

如果你有2个以上不同值，请使用COUNT DISTINCT代替，如下所示：

SELECT c.* 
FROM customer c 
JOIN (SELECT customer_id 
     FROM customer_tag 
     WHERE tag_id IN (1,2,3) 
     GROUP BY customer_id 
     HAVING COUNT(DISTINCT tag_id) = 3) ct ON c.customer_id = ct.customer_id 

Answer 4

扩展其他的答案，我会添加一个版本，你不必指望标签也列出了他们两次：

WITH tgs as(
    select distinct tag_id 
    from Tags 
    where tag_id in (1, 2, 3, 4) --modify only here 
) 
SELECT c.* 
FROM customer c 
JOIN (SELECT customer_id 
     FROM customer_tag 
     WHERE tag_id in (select tag_id from tgs) 
     GROUP BY customer_id 
     HAVING COUNT(DISTINCT tag_id) = (select count(*) from tgs) 
    ) ct ON c.customer_id = ct.customer_id 

如果表是正确标准化（并有PKS等），你可以删除distinct关键字。