blocks|key|1283742|text|下面是另一种只访问基表一次的方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1283743|SELECT+COUNT(*)+as+TotalCount
++++,SUM(case+when+Condition+=+'MyCondition'+then+1+else+0+end)+as+ConditionalCount
FROM+[MyTable]+++++|code-block|syntax|javascript|1283744|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Here is another method that only hits the base table once.

<pre><code>SELECT COUNT(*) as TotalCount
 ,SUM(case when Condition = 'MyCondition' then 1 else 0 end) as ConditionalCount
FROM [MyTable] 
</code></pre>

blocks|key|479858|text|您可以简单地将计数的匹配除以记录总数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|479859|样本数据：|offset|length|style|BOLD|479860|create+table+test+(MatchColumn+int)

insert+into+test+(MatchColumn)
values+(1),(1),(1),(2),(3),(4)|code-block|syntax|javascript|479861|匹配条件：|479862|SELECT+COUNT(*)+MatchValues,+
++++++(SELECT+COUNT(*)+FROM+test)+TotalRecords,
++++++CAST(COUNT(*)+AS+FLOAT)/CAST((SELECT+COUNT(*)+FROM+test)+AS+FLOAT)*100+Percentage
FROM+[test]+++++
WHERE+MatchColumn=1|479863|返回：|479864|%7C+MATCHVALUES+%7C+TOTALRECORDS+%7C+PERCENTAGE+%7C
%7C-------------%7C--------------%7C------------%7C
%7C+++++++++++3+%7C++++++++++++6+%7C+++++++++50+%7C|479865|SQL+Fiddle演示|479866|使用CTE：：|479867|另一个选项是对CTE进行同样的操作，并引用它创建的列：|479868|;WITH+CTE+AS+
++(SELECT+COUNT(*)+MatchValues,+
++++++(SELECT+COUNT(*)+FROM+test)+TotalRecords++++++
+++FROM+[test]+++++
+++WHERE+MatchColumn=1)
SELECT+MatchValues,+TotalRecords,+
+++++++CAST(MatchValues+AS+FLOAT)/CAST(TotalRecords+AS+FLOAT)*100+Percentage
FROM+CTE|479869|SQL+Fiddle演示|479870|注意：将计数转换为float以计算百分比是必需的，因为除以2+int值将返回int，但在本例中，我们希望小数值小于0，如果它是int，则为0。|CODE|479871|参考：|479872|Server，除法返回零|479873|entityMap|0|LINK|mutability|MUTABLE|url|http://sqlfiddle.com/#!3/67425/23|1|http://technet.microsoft.com/en-us/library/ms190766(v=sql.105).aspx|2|http://sqlfiddle.com/#!3/67425/25|3|https://stackoverflow.com/questions/1666407/sql-server-division-returns-zero^0|0|0|5|0|0|0|5|0|0|0|3|0|0|0|C|0|0|6|1|0|7|3|1|0|0|0|C|2|0|0|3|9|5|V|3|12|3|1R|3|0|0|3|0|0|C|3|0^^$0|@$1|2|3|4|5|6|7|1P|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1Q|8|@$D|1R|E|1S|F|G]]|9|@]|A|$]]|$1|H|3|I|5|J|7|1T|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|1U|8|@$D|1V|E|1W|F|G]]|9|@]|A|$]]|$1|O|3|P|5|J|7|1X|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|1Y|8|@$D|1Z|E|20|F|G]]|9|@]|A|$]]|$1|S|3|T|5|J|7|21|8|@]|9|@]|A|$K|L]]|$1|U|3|V|5|6|7|22|8|@]|9|@$D|23|E|24|1|25]]|A|$]]|$1|W|3|X|5|6|7|26|8|@$D|27|E|28|F|G]]|9|@]|A|$]]|$1|Y|3|Z|5|6|7|29|8|@]|9|@$D|2A|E|2B|1|2C]]|A|$]]|$1|10|3|11|5|J|7|2D|8|@]|9|@]|A|$K|L]]|$1|12|3|13|5|6|7|2E|8|@]|9|@$D|2F|E|2G|1|2H]]|A|$]]|$1|14|3|15|5|6|7|2I|8|@$D|2J|E|2K|F|G]|$D|2L|E|2M|F|16]|$D|2N|E|2O|F|16]|$D|2P|E|2Q|F|16]|$D|2R|E|2S|F|16]]|9|@]|A|$]]|$1|17|3|18|5|6|7|2T|8|@$D|2U|E|2V|F|G]]|9|@]|A|$]]|$1|19|3|1A|5|6|7|2W|8|@]|9|@$D|2X|E|2Y|1|2Z]]|A|$]]|$1|1B|3|-4|5|6|7|30|8|@]|9|@]|A|$]]]|1C|$1D|$5|1E|1F|1G|A|$1H|1I]]|1J|$5|1E|1F|1G|A|$1H|1K]]|1L|$5|1E|1F|1G|A|$1H|1M]]|1N|$5|1E|1F|1G|A|$1H|1O]]]]

You can do simply divide the match of the count by the total number of records.

Sample Data:

<pre><code>create table test (MatchColumn int)

insert into test (MatchColumn)
values (1),(1),(1),(2),(3),(4)
</code></pre>

Match Condition:

<pre><code>SELECT COUNT(*) MatchValues, 
 (SELECT COUNT(*) FROM test) TotalRecords,
 CAST(COUNT(*) AS FLOAT)/CAST((SELECT COUNT(*) FROM test) AS FLOAT)*100 Percentage
FROM [test] 
WHERE MatchColumn=1
</code></pre>

Returns:

<pre><code>| MATCHVALUES | TOTALRECORDS | PERCENTAGE |
|-------------|--------------|------------|
| 3 | 6 | 50 |
</code></pre>

<h2><a href="http://sqlfiddle.com/#!3/67425/23" rel="nofollow noreferrer">SQL Fiddle Demo</a></h2>

Using a CTE:

Another option is to do the same with a <a href="http://technet.microsoft.com/en-us/library/ms190766(v=sql.105).aspx" rel="nofollow noreferrer">CTE</a> and reference the columns it creates:

<pre><code>;WITH CTE AS 
 (SELECT COUNT(*) MatchValues, 
 (SELECT COUNT(*) FROM test) TotalRecords 
 FROM [test] 
 WHERE MatchColumn=1)
SELECT MatchValues, TotalRecords, 
 CAST(MatchValues AS FLOAT)/CAST(TotalRecords AS FLOAT)*100 Percentage
FROM CTE
</code></pre>

<h2><a href="http://sqlfiddle.com/#!3/67425/25" rel="nofollow noreferrer">SQL Fiddle Demo</a></h2>

NOTE: Casting the counts to a <code>float</code> to calculate a percentage is required as dividing 2 <code>int</code> values would return an <code>int</code>, but in this case we want a decimal value less than 0, which would simply be 0 if it were an <code>int</code>.

Reference: 

<h2><a href="https://stackoverflow.com/questions/1666407/sql-server-division-returns-zero">SQL Server, division returns zero</a></h2>

blocks|key|479886|text|或者类似这样的东西。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|479887|create+table+test+(MatchColumn+int)
insert+into+test+(MatchColumn)
values+(1),(1),(1),(2),(3),(4)

SELECT
(SELECT+COUNT(*)+FROM+test+WHERE+MatchColumn=1)+MatchValues,+
(SELECT+COUNT(*)+FROM+test)+TotalRecords,
((SELECT+CAST(COUNT(*)+AS+FLOAT)+FROM+test+WHERE+MatchColumn=1)/CAST((SELECT+COUNT(*)+FROM+test)+AS+FLOAT)*100)+Percentage|code-block|syntax|javascript|479888|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Or something like this.

<pre><code>create table test (MatchColumn int)
insert into test (MatchColumn)
values (1),(1),(1),(2),(3),(4)

SELECT
(SELECT COUNT(*) FROM test WHERE MatchColumn=1) MatchValues, 
(SELECT COUNT(*) FROM test) TotalRecords,
((SELECT CAST(COUNT(*) AS FLOAT) FROM test WHERE MatchColumn=1)/CAST((SELECT COUNT(*) FROM test) AS FLOAT)*100) Percentage
</code></pre>

Pretty simple question I suppose, but I can't find the answer on here!

I am trying to calculate the volume of records based on a WHERE clause, as well as return a percentage of those records based on the same where clause. The percentage would be calculated against the total amount of records in the database. For example, I count all my records that meet "MyCondition":

<pre><code>SELECT COUNT(*) FROM [MyTable] 
WHERE Condition='MyCondition'
</code></pre>

This works fine. However, how does one take that count, and return the percentage it equates to when put against all the records in the database? In other words, I want to see the percentage of how many records meet WHERE Condition='MyCondition' in regards to the total record count.

Sorry for the simple question and TIA! I am using MS SQL 2012.

Using COUNT and Return Percentage Against SUM of Records

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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我想问题很简单，但我在这里找不到答案！我试图根据WHERE子句计算记录量，并根据同一where子句返回这些记录的百分比。该百分比将根据数据库中的记录总数计算。例如，我计算所有符合“MyCondition”的记录：SELECT COUNT(*) FROM [MyTable]     WHERE Condition='My...

问对记录和使用计数和返回百分比
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