Difference between revisions of "Aggregates with DISTINCT"

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Line 5: Line 5:
 
   <p>You can find the number of <i>different</i> values using COUNT with DISTINCT</p>
 
   <p>You can find the number of <i>different</i> values using COUNT with DISTINCT</p>
 
   <p>In 1915 four prizes were awarded in three different subjects:</p>
 
   <p>In 1915 four prizes were awarded in three different subjects:</p>
<table><td><pre>SELECT yr, subject, winner
+
<table class='NoBorder'><td><pre>SELECT yr, subject, winner
 
   FROM nobel
 
   FROM nobel
 
  WHERE yr=1915</pre>
 
  WHERE yr=1915</pre>
 
</td><td>
 
</td><td>
<table border="1" class="restable" style=""><tr>
+
<table border="1" class="Bordered" style=""><tr>
 
<th>yr</th>
 
<th>yr</th>
 
<th>subject</th>
 
<th>subject</th>

Latest revision as of 08:23, 18 July 2012

Nobel database

COUNT DISTINCT

You can find the number of different values using COUNT with DISTINCT

In 1915 four prizes were awarded in three different subjects:

SELECT yr, subject, winner
  FROM nobel
 WHERE yr=1915
yr subject winner
1915 Chemistry Richard Willstätter
1915 Literature Romain Rolland
1915 Physics Lawrence Bragg
1915 Physics William Bragg

COUNT(subject) gives 4; COUNT(DISTINCT subject) gives 3.

SELECT COUNT(subject), COUNT(DISTINCT subject)
  FROM nobel
 WHERE yr = 1915
SELECT COUNT(subject), COUNT(DISTINCT subject)
  FROM nobel
 WHERE yr = 1915
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