blocks|key|2249005|text|CASE语句中的整数值不是列序数，而是将用于排序结果的静态整数值。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2249006|在通过substring(issue,+1,+4)+DESC订购记录之后，|2249007|当substring(issue,+6,+100)为'Winter'或'First_Quarter'时，首先对其进行排序，|2249008|当substring(issue,+6,+100)是'Summer'或'Second_Quarter'时，它将按'Winter'或'First_Quarter'排序。|2249009|以此类推。|2249010|为了更好地理解，您可以选择案例并查看结果。|2249011|SELECT+npID,+title,+URL,+issue,CASE+
++++++++++WHEN+substring(issue,+6,+100)+IN+('Winter','First_Quarter')++THEN+1
++++++++++WHEN+substring(issue,+6,+100)+IN+('Summer','Second_Quarter')+THEN+2
++++++++++WHEN+substring(issue,+6,+100)+IN+('Spring','Third_Quarter')++THEN+3
++++++++++WHEN+substring(issue,+6,+100)+IN+('Fall',++'Fourth+Quarter')+THEN+4
++++++++++ELSE+5+
+++++++END
FROM+++tbl
ORDER++BY+substring(issue,+1,+4)+DESC
++++++,CASE+
++++++++++WHEN+substring(issue,+6,+100)+IN+('Winter','First_Quarter')++THEN+1
++++++++++WHEN+substring(issue,+6,+100)+IN+('Summer','Second_Quarter')+THEN+2
++++++++++WHEN+substring(issue,+6,+100)+IN+('Spring','Third_Quarter')++THEN+3
++++++++++WHEN+substring(issue,+6,+100)+IN+('Fall',++'Fourth+Quarter')+THEN+4
++++++++++ELSE+5+
+++++++END;|code-block|syntax|javascript|2249012|entityMap^0|0|4|0|3|R|0|1|O|Q|8|Z|F|0|1|O|Q|8|Z|G|1K|8|1T|F|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@$9|10|A|11|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|12|8|@$9|13|A|14|B|C]|$9|15|A|16|B|C]|$9|17|A|18|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|19|8|@$9|1A|A|1B|B|C]|$9|1C|A|1D|B|C]|$9|1E|A|1F|B|C]|$9|1G|A|1H|B|C]|$9|1I|A|1J|B|C]]|D|@]|E|$]]|$1|L|3|M|5|6|7|1K|8|@]|D|@]|E|$]]|$1|N|3|O|5|6|7|1L|8|@]|D|@]|E|$]]|$1|P|3|Q|5|R|7|1M|8|@]|D|@]|E|$S|T]]|$1|U|3|-4|5|6|7|1N|8|@]|D|@]|E|$]]]|V|$]]

The integer values present in <code>CASE</code> statement are not column ordinals those are static Integer values that will be used to order the result.

After ordering the records by <code>substring(issue, 1, 4) DESC</code>, 

when <code>substring(issue, 6, 100)</code> is <code>'Winter'</code> or <code>'First_Quarter'</code> then it will be sorted first, 

when <code>substring(issue, 6, 100)</code> is <code>'Summer'</code> or <code>'Second_Quarter'</code> then it will sort after <code>'Winter'</code> or <code>'First_Quarter'</code>

and so on..

For better understanding you can select the case and see the result

<pre><code>SELECT npID, title, URL, issue,CASE 
 WHEN substring(issue, 6, 100) IN ('Winter','First_Quarter') THEN 1
 WHEN substring(issue, 6, 100) IN ('Summer','Second_Quarter') THEN 2
 WHEN substring(issue, 6, 100) IN ('Spring','Third_Quarter') THEN 3
 WHEN substring(issue, 6, 100) IN ('Fall', 'Fourth Quarter') THEN 4
 ELSE 5 
 END
FROM tbl
ORDER BY substring(issue, 1, 4) DESC
 ,CASE 
 WHEN substring(issue, 6, 100) IN ('Winter','First_Quarter') THEN 1
 WHEN substring(issue, 6, 100) IN ('Summer','Second_Quarter') THEN 2
 WHEN substring(issue, 6, 100) IN ('Spring','Third_Quarter') THEN 3
 WHEN substring(issue, 6, 100) IN ('Fall', 'Fourth Quarter') THEN 4
 ELSE 5 
 END;
</code></pre>

blocks|key|2249072|text|在ORDER子句中的CASE语句是否返回列序号？|type|blockquote|depth|inlineStyleRanges|entityRanges|data|2249073|不是的。|unstyled|2249074|下面的语句更改仅在该列中显示值的顺序。|2249075|CASE+
++++++++++WHEN+substring(issue,+6,+100)+IN+('Winter','First_Quarter')++THEN+1
++++++++++WHEN+substring(issue,+6,+100)+IN+('Summer','Second_Quarter')+THEN+2
++++++++++WHEN+substring(issue,+6,+100)+IN+('Spring','Third_Quarter')++THEN+3
++++++++++WHEN+substring(issue,+6,+100)+IN+('Fall',++'Fourth+Quarter')+THEN+4
++++++++++ELSE+5+
+++++++END;*emphasized+text*|code-block|syntax|javascript|2249076|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|O|8|@]|9|@]|A|$]]|$1|E|3|F|5|D|7|P|8|@]|9|@]|A|$]]|$1|G|3|H|5|I|7|Q|8|@]|9|@]|A|$J|K]]|$1|L|3|-4|5|D|7|R|8|@]|9|@]|A|$]]]|M|$]]

<blockquote>
 does a CASE statement in an ORDER BY clause return column ordinals?
</blockquote>

No.

Below statement changes order in which the values appear in that column only

<pre><code>CASE 
 WHEN substring(issue, 6, 100) IN ('Winter','First_Quarter') THEN 1
 WHEN substring(issue, 6, 100) IN ('Summer','Second_Quarter') THEN 2
 WHEN substring(issue, 6, 100) IN ('Spring','Third_Quarter') THEN 3
 WHEN substring(issue, 6, 100) IN ('Fall', 'Fourth Quarter') THEN 4
 ELSE 5 
 END;*emphasized text*
</code></pre>

blocks|key|2728515|text|这些整数不是列序数，而是值文本。该查询首先按照issue列的前四个字符(代表年份)进行排序。然后，根据case表达式表示的第二个键对它们进行排序。在那里使用的值本身并不有趣，只有它们之间的相对顺序是重要的。例如，计算夏季问题的2没有任何意义--只有在冬天之后(计算为1)和春天之前(计算为3)。查询可以使用'a‘、'b’、'c‘、'd’和'e‘，并得到完全相同的结果。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2728516|entityMap^0|N|5|1F|4|35|1|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|O|8|@]|D|@]|E|$]]]|G|$]]

These integers aren't column ordinals, but value literals. The query is first sorted by the first four characters of the <code>issue</code> column (representing the year). Then, they are ordered according to a secondary key represented by the the <code>case</code> expression. The values used there aren't interesting on their own right, only the relative order between them is important. E.g., <code>2</code>, calculated for summer issues has no meaning - only that it comes after winter (calculated as 1) and before spring (calculated as 3). The query could have used 'a', 'b', 'c', 'd' and 'e' instead and got the exact same result.

blocks|key|2728555|text|ORDER+BY子句中唯一一项被认为是序数的情况是，当它是整数字面时，看看SQL92标准，我们可以看到它的起源：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2728556|如果a包含a，则该值应大于0而不大于T的度数。|blockquote|2728557|如果ORDER+BY子句包含一个非常量标量表达式(如CASE+)，则该表达式的结果被用作排序键，也就是说，如果它计算结果集中的一行并返回整数n，则它是排序的n的值。|2728558|entityMap|0|LINK|mutability|MUTABLE|url|https://msdn.microsoft.com/en-us/library/ms188385.aspx#Case^0|0|8|0|0|2|8|Q|4|Q|4|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$]]|$1|I|3|J|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@$9|11|A|12|1|13]]|E|$]]|$1|K|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

The only time an item in a <code>ORDER BY</code> clause is considered to be an ordinal is when its an integer literal, looking at the sql-92 standard we can see the origin of this:

<blockquote>
 If a &lt;sort specification&gt; contains an &lt;unsigned integer&gt;, then the
 &lt;unsigned integer&gt; shall be greater than 0 and not greater than the
 degree of T. The &lt;sort specification> identifies the column of T with
 the ordinal position specified by the &lt;unsigned integer&gt;.
</blockquote>

If the <code>ORDER BY</code> clause contains a non-constant scalar expression such as <a href="https://msdn.microsoft.com/en-us/library/ms188385.aspx#Case" rel="nofollow noreferrer"><code>CASE</code></a> then the result of that expression is used as the sort key, i.e. if it evaluates a row in the result set and returns an integer n it is the value of n that is sorted upon.

I ran across a suggestion here (<a href="https://stackoverflow.com/questions/8187828/sql-order-by-using-a-substring-within-a-specific-column-possible">SQL: ORDER BY using a substring within a specific column... possible?</a>) that shows a CASE statement returning integers inside an ORDER BY clause on a table with 4 columns.

<pre><code>SELECT npID, title, URL, issue
FROM tbl
ORDER BY substring(issue, 1, 4) DESC
 ,CASE 
 WHEN substring(issue, 6, 100) IN ('Winter','First_Quarter') THEN 1
 WHEN substring(issue, 6, 100) IN ('Summer','Second_Quarter') THEN 2
 WHEN substring(issue, 6, 100) IN ('Spring','Third_Quarter') THEN 3
 WHEN substring(issue, 6, 100) IN ('Fall', 'Fourth Quarter') THEN 4
 ELSE 5 
 END;
</code></pre>

I do not understand how this works. Clearly the integers that result from the CASE are NOT column ordinals (for example, the ELSE 5, since the table has only 4 columns). But what do they mean? -- The context makes it seem as if they are to be used THEMSELVES for ordering on, but I've never seen this kind of thing in an ORDER BY. (However, the example given in the post works, so I am really perplexed.) Can someone explain what it means to return integers inside a CASE statement inside an ORDER BY clause? Thank you.

MSSQL - does a CASE statement in an ORDER BY clause return column ordinals?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我在这里遇到了一个建议()，它显示了一个CASE语句，它在一个包含4列的表中返回ORDER子句中的整数。SELECT npID, title, URL, issueFROM   tblORDER  BY substring(issue, 1, 4) DESC      ,CASE           WHEN subs...

问MSSQL -在ORDER子句中的CASE语句是否返回列序号？
EN

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问MSSQL -在ORDER子句中的CASE语句是否返回列序号？EN