连接两个SELECT语句

Question

连接两个SELECT语句

36

有人能告诉我为什么以下代码无法正常工作吗？它会抱怨在两个select之间的join关键字附近有一个语法错误。

SELECT * 
FROM ( select * from orders_products inner JOIN orders ON orders_products.orders_id = orders.orders_id  where products_id = 181) 
as A

join 

SELECT * 
FROM ( select * from orders_products INNER JOIN orders ON orders_products.orders_id = orders.orders_id  where products_id = 180) 
as B

on A.orders_id=B.orders_id

基本上，我的第一个SELECT从一张表中获取某个产品的所有订单信息，并从另一张表中获取订购数量，然后将它们连接起来。第二个SELECT对另一个产品执行相同的操作。

现在，我有了

_______A_________         _______B_________

O_ID   P_ID   Q            O_ID   P_ID   Q 

1       180   3            1       181   11

2       180   9            2       181   6

3       180   5            3       181   3

并且，使用另一个连接，我想要得到


Q_ID   P_ID1   Q1    P_ID2    Q2

1       180    3      181     11

2       180    9      181      6

3       180    5      181      3

也许我在这里做错了什么。有什么建议吗？

更新：在RedFilter的指引下，以下是对我有效的内容：

(SELECT * 
FROM (
SELECT * FROM orders_products
INNER JOIN orders ON orders_products.orders_id = orders.orders_id
WHERE products_id =181) AS A
LEFT JOIN (
SELECT * FROM orders_products
INNER JOIN orders ON orders_products.orders_id = orders.orders_id
WHERE products_id =180) AS B ON A.orders_id = B.orders_id
)
UNION (
SELECT * 
FROM (
SELECT * 
FROM orders_products
INNER JOIN orders ON orders_products.orders_id = orders.orders_id
WHERE products_id =181
) AS C
RIGHT JOIN (
SELECT * 
FROM orders_products
INNER JOIN orders ON orders_products.orders_id = orders.orders_id
WHERE products_id =180
) AS D ON C.orders_id = D.orders_id
)

- Codrguy

3

所有的加入看起来有点不必要。 - Naftali

1

你能描述一下你想从这个查询中检索什么吗？可能有更有效率的方法。 - John Kane

4个回答

12

如果您想要合并不同的结果集，可以使用UNION。请尝试以下操作：

(SELECT * 
 FROM ( SELECT * 
        FROM orders_products 
        INNER JOIN orders ON orders_products.orders_id = orders.orders_id  
        WHERE products_id = 181) AS A)
UNION 

(SELECT * 
 FROM ( SELECT * 
        FROM orders_products 
        INNER JOIN orders ON orders_products.orders_id = orders.orders_id 
        WHERE products_id = 180) AS B
ON A.orders_id=B.orders_id)

- alexn

3

这将实现您想要的功能：

select * 
  from orders_products 
       INNER JOIN orders 
          ON orders_products.orders_id = orders.orders_id
 where products_id in (180, 181);

- maple_shaft

-1

SELECT *
FROM
  (First_query) AS ONE
LEFT OUTER JOIN
  (Second_query ) AS TWO ON ONE.First_query_ID = TWO.Second_Query_ID;

- Narendra Kumar Achari

请在您的答案中添加一个探索。 - Gregor Doroschenko

选择 * 从 (SELECT c.name AS COUNTRY_NAME
FROM STATS_TABLE ebs INNER JOIN CLASS_TABLE ebsec ON ebs.ID = ebsec.STATS_TABLE_id AND ebs.USER_ID = ebsec.user_id INNER JOIN classes ec ON ebsec.class_id = ec.id WHERE ebs.created_at blabla GROUP BY es.id) AS ea LEFT OUTER JOIN (SELECT es.School_id
FROM STATS_TABLE ebs INNER JOIN CLASS_TABLE ebsec ON ebs.ID = ebsec.STATS_TABLE_id AND USER_ID = ebsec.user_id WHERE ebs.STATUS IN ('COMPLETED') AND ebs.creted GROUP BY es.id) AS ear ON ea.School_id = ear.School_id; - Narendra Kumar Achari

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- D'Arcy Rittich · Accepted Answer

不确定你想做什么，但是你有两个select子句。请改为这样：

SELECT * 
FROM ( SELECT * 
       FROM orders_products 
       INNER JOIN orders ON orders_products.orders_id = orders.orders_id 
       WHERE products_id = 181) AS A
JOIN ( SELECT * 
       FROM orders_products 
       INNER JOIN orders ON orders_products.orders_id = orders.orders_id
       WHERE products_id = 180) AS B

ON A.orders_id=B.orders_id

更新：

你可能可以将它简化为像这样的内容：

SELECT o.orders_id, 
       op1.products_id, 
       op1.quantity, 
       op2.products_id, 
       op2.quantity
FROM orders o
INNER JOIN orders_products op1 on o.orders_id = op1.orders_id  
INNER JOIN orders_products op2 on o.orders_id = op2.orders_id  
WHERE op1.products_id = 180
AND op2.products_id = 181