MySQL 按子查询排序答案

【问题标题】：MySQL Ordering by SubQueryMySQL 按子查询排序
【发布时间】：2015-10-28 14:59:44
【问题描述】：

我正在尝试提取下订单最多的客户列表。我似乎无法弄清楚如何保持子查询对列表进行排序。这是我的查询：

SELECT
  c.*,
  state.abbreviation AS state,
  country.abbreviation AS country
FROM main_customers AS c
  LEFT JOIN dict_stateProvince AS state ON c.state = state.id
  LEFT JOIN dict_country AS country ON c.country = country.id
WHERE c.id IN (SELECT customerId
               FROM main_orders
               GROUP BY customerId
               ORDER BY COUNT(*) DESC)
LIMIT 50;

如何保持主查询与子查询的顺序一致？

【问题讨论】：

标签： mysql group-by subquery sql-order-by

【解决方案1】：

您的子查询没有真正的顺序，因为IN 忽略了顺序。但意图很明确。所以，使用join：

SELECT c.*,
       state.abbreviation AS state,
       country.abbreviation AS country
FROM main_customers AS c JOIN
     (SELECT customerId, COUNT(*) as cnt
      FROM main_orders
      GROUP BY customerId
     ) mo
     ON mo.customerId = c.id LEFT JOIN
     dict_stateProvince AS state
     ON c.state = state.id LEFT JOIN
     dict_country AS country
     ON c.country = country.id
ORDER BY mo.cnt DESC;

【讨论】：