Question

我希望获得每周工作时间少于每家店铺平均工作时间的工人名单。

工：

名称
小时（一个工人每周工作一小时）
商店（工人工作的商店）

这给了我一对（商店，商店的平均营业时间）列表：

SELECT shop, AVG(hours) AS 'av' FROM Workers GROUP BY shop

这是我的＆＃39; Pseudo SQL＆＃39;：

SELECT 
    name, hours, 
    (SELECT shop, AVG(hours) AS 'av' FROM Workers GROUP BY shop).av 
FROM Workers 
WHERE 
   (SELECT shop, AVG(hours) AS 'av' FROM Workers GROUP BY shop).av > Workers.hours 
   AND (SELECT shop, AVG(hours) AS 'av' FROM Workers GROUP BY shop).shop = Workers.shop

我需要在单个T-SQL查询中完成此操作。你能救我吗？

Answer 1

您可以使用Common Table Expressions：

With averageHours as (SELECT shop, AVG(hours) AS 'av' FROM Workers GROUP BY shop)
SELECT name, hours, averageHours.av
FROM Workers WHERE averageHours.av > Workers.hours 
             AND averageHours.shop = Workers.shop

Answer 2

你非常接近。我完全不了解你的查询（什么是“Pracownicy”表？），但这应该给你一个想法（未经测试的查询）：

SELECT w.name,
       w.hours,
       w.shop,
       avg.average
  FROM Workers AS w,
       (SELECT shop,
               AVG(hours) AS average
          FROM Workers
        GROUP BY shop) AS avg
 WHERE w.shop = avg.shop
   AND w.hours < avg.average

请注意这里的技巧：使用查询作为FROM子句中的表。这允许您减少重复子选择的数量。

Answer 3

SELECT NAME FROM TABLE T1 WHERE T1.HOUR < ( SELECT AVG(HOUR) FROM TABLE GROUP BY T1.NAME )

这是最简单的查询，无任何混乱。

复杂的SQL Server SELECT查询

3 个答案: