关于非规范化。我怎样才能使这个查询更短或更好？ （SQL SERVER 2000）[关闭]

Posted 2023-03-12

【中文标题】关于非规范化。我怎样才能使这个查询更短或更好？ （SQL SERVER 2000）[关闭]

【英文标题】：On Denormalization. How can I make this query shorter or better? (SQL SERVER 2000) [closed]

【发布时间】：2011-09-14 09:54:48

【问题描述】：

INSERT INTO
denormalizedTable

SELECT
table1.userName,
MAX(CASE WHEN table2.Type = 1 THEN table2.Question END) AS question_1,
MAX(CASE WHEN table2.Type = 1 THEN table2.Answer END) AS answer_1,
MAX(CASE WHEN table2.Type = 2 THEN table2.Question END) AS question_2,
MAX(CASE WHEN table2.Type = 2 THEN table2.Answer END) AS answer_2,
MAX(CASE WHEN table2.Type = 3 THEN table2.Question END) AS question_3,
MAX(CASE WHEN table2.Type = 3 THEN table2.Answer END) AS answer_3,
MAX(CASE WHEN table2.Type = 4 THEN table2.Question END) AS question_4,
MAX(CASE WHEN table2.Type = 4 THEN table2.Answer END) AS answer_4,
MAX(CASE WHEN table2.Type = 5 THEN table2.Question END) AS question_5,
MAX(CASE WHEN table2.Type = 5 THEN table2.Answer END) AS answer_5,
MAX(CASE WHEN table2.Type = 6 THEN table2.Question END) AS question_6,
MAX(CASE WHEN table2.Type = 6 THEN table2.Answer END) AS answer_6,
MAX(CASE WHEN table2.Type = 7 THEN table2.Question END) AS question_7,
MAX(CASE WHEN table2.Type = 7 THEN table2.Answer END) AS answer_7,
MAX(CASE WHEN table2.Type = 8 THEN table2.Question END) AS question_8,
MAX(CASE WHEN table2.Type = 8 THEN table2.Answer END) AS answer_8

FROM
table1
JOIN
table2
ON
table1.userID = table2.userID 

GROUP BY table1.userName

【问题讨论】：

您是否考虑过将其作为索引视图来维护，而不是您必须维护的新表？ technet.microsoft.com/en-us/library/cc917717.aspx

您认为denormalizedTable 属于哪种范式？

【参考方案1】：

您正在 SQL 中执行“PIVOT”操作。没有真正更好的方法可以做，所以你不能真正让它变得更好。

也许您可以 GROUP BY table1.userID 而不是 userName！

问题是：为什么需要这样的查询？

如果您正在为客户端执行查询以在视图中返回结果，则枢轴操作必须是视图的工作，而不是 DAL。

我们需要更多的上下文来回答你！

【讨论】：

这甚至不是一个答案。为什么投票赞成？谁删除了评论？