如何使PIVOT成为表/交叉表查询？

Question

我已经执行了一条SELECT语句来获取以下输出：

MOVIE                           Critic Type  Average Rating
------------------------        ------------ --------------
30 Minutes or Less              Critic                 2.00
30 Minutes or Less              User                   4.20
A Lonely Place to Die           Critic                10.00
A Lonely Place to Die           User                   8.50
Taken                           Critic                 6.17
Taken                           User                   7.27
Taken 2                         Critic                 4.00
Taken 2                         User                   6.29

8 rows selected

这是SELECT语句：

SELECT MovieTitle AS "MOVIE", TBLCRITICCLASS.CRITICCLASSDESC AS "Critic Type", AVG(TBLREVIEW.REVIEWSTAR) AS "Average Rating"
FROM TBLMOVIE 
INNER JOIN TBLREVIEW ON TBLMOVIE.MOVIEID = TBLREVIEW.MOVIEID 
INNER JOIN TBLCRITIC ON TBLREVIEW.CRITICID = TBLCRITIC.CRITICID 
INNER JOIN TBLCRITICCLASS ON TBLCRITIC.CRITICCLASSID = TBLCRITICCLASS.CRITICCLASSID 
GROUP BY MovieTitle, TBLCRITICCLASS.CRITICCLASSDESC
ORDER BY Movietitle;

我想用PIVOT将此表转换为此输出，以得到具有评论者评分和用户评分的输出，因为它是其自己的类别：

MOVIE                           Critic Rating   User Rating
------------------------        -------------   -----------
30 Minutes or Less              2.00                   4.20
A Lonely Place to Die           10.00                  8.50
Taken                           6.17                   7.27
Taken 2                         4.00                   6.29

我尝试这样做：

SELECT * FROM
(
  SELECT MovieTitle AS "MOVIE", AVG(TBLREVIEW.REVIEWSTAR) AS "Critic Rating", AVG(TBLREVIEW.REVIEWSTAR) AS "User Rating"
  FROM TBLMOVIE 
  INNER JOIN TBLREVIEW ON TBLMOVIE.MOVIEID = TBLREVIEW.MOVIEID 
  INNER JOIN TBLCRITIC ON TBLREVIEW.CRITICID = TBLCRITIC.CRITICID 
  INNER JOIN TBLCRITICCLASS ON TBLCRITIC.CRITICCLASSID = TBLCRITICCLASS.CRITICCLASSID 
  GROUP BY MovieTitle, TBLCRITICCLASS.CRITICCLASSDESC
  ORDER BY Movietitle
)

PIVOT
(
  AVG(TBLREVIEW.REVIEWSTAR) AS "Critic Rating"
  FOR TBLREVIEW.REVIEWSTAR IN (TBLCRITICCLASS.CRITICCLASSDESC)

  AVG(TBLREVIEW.REVIEWSTAR) AS "User Rating"
  FOR TBLREVIEW.REVIEWSTAR IN (TBLCRITICCLASS.CRITICCLASSDESC)
)

我收到错误，这可能是由于我缺乏对子查询的技巧，我想了解为什么我没有得到我喜欢的输出以及如何解决它。

编辑：

以下是相关的表：

File1（Pastebin）

File2（Pastebin）

Answer 1

您只是将枢纽声明弄错了。 您可以将查询替换为下面的CTE，它应该可以工作。

SELECT * 
FROM (SELECT MovieTitle AS "MOVIE"
           , TBLCRITICCLASS.CRITICCLASSDESC AS      "Critic Type"
           , AVG(TBLREVIEW.REVIEWSTAR) AS "Average Rating"
      FROM TBLMOVIE 
      INNER JOIN TBLREVIEW 
        ON TBLMOVIE.MOVIEID = TBLREVIEW.MOVIEID 
      INNER JOIN TBLCRITIC 
        ON TBLREVIEW.CRITICID = TBLCRITIC.CRITICID 
      INNER JOIN TBLCRITICCLASS 
        ON TBLCRITIC.CRITICCLASSID = TBLCRITICCLASS.CRITICCLASSID 
      GROUP BY MovieTitle, TBLCRITICCLASS.CRITICCLASSDESC
      )
PIVOT (AVG("Average Rating") for "Critic Type" 
   in ('Critic' as "Critic Rating", 'User' as "User Rating")))
ORDER BY Movie

关于“为什么我没有得到我的首选输出”

您正在使用“临界类型”，因为它具有两个值（“临界”和“用户”），所以avg是有意义的； 但在您的示例中，每条记录只有1个值，因此最小/最大也会起作用。

在数据透视图中，您可以在数据透视的“输入”部分中指定每一列，让数据库引擎根据“关键类型”列中的值确定如何组织数据。

因为必须指定每个值，所以如果没有动态SQL，就无法拥有动态范围。

注意：如果您希望使用与“ for”数据透视表字段中的值不同的名称，则可以对数据透视表的“ IN”部分中的列进行别名命名。