Question

我有以下查询正常工作。

  SELECT d.customer_id,
          d.fname,
          d.lname,
          m.lastDate,
     (SELECT COUNT(order_id)
      FROM `orders`
      WHERE `customer_id`=d.customer_id
      ) AS 'total_orders',
          d.isActive
   FROM customers d
   JOIN `orders` m ON m.order_id=
     (SELECT order_id
      FROM `orders`
      WHERE customer_id=d.customer_id
      ORDER BY order_id DESC LIMIT 1
      )
   WHERE d.user_id=382
     AND d.customer_id NOT IN
       (SELECT `customer_id`
        FROM `orders`
        WHERE `balance`>0
          AND `isActive`=1
        )

上面的查询工作正常但是当添加和联合查询还包括没有下任何订单的客户时，它确实有效。

   SELECT d.customer_id,
          d.fname,
          d.lname,
          m.lastDate,
     (SELECT COUNT(order_id)
      FROM `orders`
      WHERE `customer_id`=d.customer_id
      ) AS 'total_orders',
          d.isActive
   FROM customers d
   JOIN `orders` m ON m.order_id=
     (SELECT order_id
      FROM `orders`
      WHERE customer_id=d.customer_id
      ORDER BY order_id DESC LIMIT 1
      )
   WHERE d.user_id=382
     AND d.customer_id NOT IN
       (SELECT `customer_id`
        FROM `orders`
        WHERE `balance`>0
          AND `isActive`=1
        )

UNION 

#customer WITH NO ORDERS
  SELECT `customer_id`,`fname`,`lname`,`state`,`city`,`isActive`
   FROM `customers`
   WHERE `user_id`=382
     AND `isActive` >-1
     AND `customer_id` NOT IN
       (SELECT `customer_id`
        FROM `orders`
        )

它在我的phpmyadmin中显示此错误

此类型的子句先前已被解析（接近选择）

Answer 1

根据您的评论，我认为您不想使用union - 您想要使用outer join。以下是使用joins而非所有correlated subqueries的查询的略微简化版本。

SELECT  d.customer_id, d.fname, d.lname, d.isactive,
        o.lastdate, 
        Count(o2.order_id) AS 'total_orders'
 FROM   customers d 
        LEFT JOIN (SELECT MAX(order_id) order_id, customer_id
              FROM   orders 
              GROUP BY customer_id) m on d.customer_id = m.customer_id
        LEFT JOIN orders o on m.order_id = o.order_id
        LEFT JOIN orders o2 on d.customer_id = o2.customer_id 
                           AND o2.balance > 0 AND o2.isactive = 1
 WHERE  d.user_id = 382 
        AND o2.customer_id IS NULL
 GROUP BY d.customer_id

BTW - 在使用union语句时，检查您的修改时，每个select列表中的列数必须相同。第二个查询中的state和city字段可能与第一个查询中的lastDate和count字段的数据类型不同。

之前解析过这种类型的子句

1 个答案: