Question

有一个产品表和一个产品标签表。
尝试选择具有所有标签的所有产品。因此，当用户优化搜索时，他们只会获得带有所有标签的产品。

标签

id              PID       tag
------------------------------
0c212c04_Gold   0c212c04  Gold
0c212c04_500g   0c212c04  500g
0c212c04_Coin   0c212c04  Coin

最初，我尝试了OR和IN，但结果返回了所有。即使他们只有一个必需的标记

SELECT DISTINCT p.* 
FROM products p
INNER JOIN product_tags pt ON (p.PID = pt.PID)
WHERE pt.tag = 'Gold' OR pt.tag = '10oz' AND p.RRP BETWEEN 0 AND 1000000

SELECT DISTINCT p.* 
FROM products p
INNER JOIN product_tags pt ON (p.PID = pt.PID)
WHERE pt.tag IN ('Gold','10oz') AND p.RRP BETWEEN 0 AND 1000000

因此，我尝试了AND，它带来了 0 个结果。

SELECT DISTINCT p.* 
FROM products p
INNER JOIN product_tags pt ON (p.PID = pt.PID)
WHERE pt.tag = 'Gold' AND pt.tag = '10oz' AND p.RRP BETWEEN 0 AND 1000000

如何带回带有多个标签Gold和10oz和Coin的所有产品？

Answer 1

您可以使用HAVING子句：

SELECT p.* 
FROM products p JOIN
     product_tags pt 
     ON p.PID = pt.PID
WHERE pt.tag IN ('Gold', '10oz') AND 
      p.RRP BETWEEN 0 AND 1000000
GROUP BY p.PID  -- okay assuming PID is unique/primary key
HAVING COUNT(*) = 2;

Answer 2

这是一个依赖条件聚合的选项，它可以处理任意数量的条件（只需向HAVING子句添加更多条件）：

SELECT p.id
FROM products p
INNER JOIN product_tags pt ON p.PID = pt.PID
WHERE p.rrp BETWEEN 0 AND 1000000
GROUP BY p.id
HAVING MAX(pt.tag = 'GOLD') = 1 AND MAX(pt.tag = '10oz') = 1

注意：如果您需要products中的更多列，则需要在SELECT子句的GROUP BY 和中添加它们（这不会因为主键product.id已经在非聚合列中，所以会影响查询结果。

MYSQL从同一表中选择并连接多个where AND子句

2 个答案: