除了视图之外的子查询的替代

Question

感谢您查看我的帖子，感谢任何帮助/指导。我的SQL技能缺乏，我尝试了几种解决方案但没有成功。无论如何，我需要为以下查询创建一个VIEW：

CREATE VIEW open_orders AS
SELECT
 t1.orderID,
 DATE_FORMAT(t1.orderDate,'%m-%d-%Y') AS orderDate,
 t6.colorName,
 t1.originID,
 t1.rackNumber,
 t2.locationNumber AS originNumber,
 t2.locationName AS originName,
 t3.locationName AS destinationName,
 t4.locationStatusName,
 COUNT(t5.orderID) AS totalCount
FROM `order` AS t1
JOIN `location` AS t2 ON t1.originID = t2.locationID
JOIN `location` AS t3 ON t1.destinationID = t3.locationID
JOIN `locationStatus` AS t4 ON t1.locationStatusID = t4.locationStatusID
LEFT JOIN (SELECT * FROM `orderItem` WHERE `productStatusID` = 02 OR `productStatusID` = 03) AS t5 ON t1.orderID = t5.orderID
JOIN `color` AS t6 ON t1.requestedColorID = t6.colorID
WHERE t1.orderStatusID = 01
GROUP BY t1.orderID
ORDER BY t1.orderDate DESC, t1.orderID DESC;

问题在于子查询。因为我无法在FROM语句中使用子查询，所以我尝试使用VIEW。但是，该表很大，这种方法会导致太多的性能问题。

我确信有一种方法可以在不使用VIEW或子查询的情况下完成此操作，但我无法提出解决方案。

感谢任何帮助/指导。

Answer 1

您不需要子查询。

...
LEFT JOIN orderItem AS t5
       ON t5.orderID = t1.orderID
      AND t5.productStatusID IN (02,03)
JOIN color ...

这与您的查询完全相同，但更有效率，因为它避免了派生表。