Question

任何人都可以看到为什么第二个结果集产生0结果的任何原因，即使我独立运行查询第二个将返回结果??

SELECT GROUP_CONCAT(DISTINCT(mu.ID)) AS users
FROM `companies` c
JOIN `companysites` cs ON c.ID = cs.companyID
JOIN `users` mu ON cs.ID = mu.siteID
JOIN `targetcategories` tcat ON c.smTargetCategory = tcat.ID
WHERE isVendor = 0;

SET @in = "users";

SELECT *
FROM privileges
WHERE userID IN (@in);

我实际上需要将第二个查询作为删除查询，但希望在我执行之前检查结果。

Answer 1

在子查询中传递您的第一个查询，以进行删除：

DELETE FROM privileges
WHERE userID IN (
  SELECT GROUP_CONCAT(DISTINCT(mu.ID)) AS userID
  FROM `companies` c
  JOIN `companysites` cs ON c.ID = cs.companyID
  JOIN `users` mu ON cs.ID = mu.siteID
  JOIN `targetcategories` tcat ON c.smTargetCategory = tcat.ID
  WHERE isVendor = 0
);

如果mysql返回错误，您可以尝试“封装”子查询：

DELETE p.*
FROM privileges p
WHERE userID IN (
    SELECT userID
    FROM 
        (SELECT GROUP_CONCAT(DISTINCT(mu.ID)) AS userID
        FROM `companies` c
        JOIN `companysites` cs ON c.ID = cs.companyID
        JOIN `users` mu ON cs.ID = mu.siteID
        JOIN `targetcategories` tcat ON c.smTargetCategory = tcat.ID
        WHERE isVendor = 0) x);

集合中的第二个查询未返回结果

1 个答案: