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  • Committer: Monty Taylor
  • Date: 2011-02-13 17:26:39 UTC
  • mfrom: (2157.2.2 give-in-to-pkg-config)
  • mto: This revision was merged to the branch mainline in revision 2166.
  • Revision ID: mordred@inaugust.com-20110213172639-nhy7i72sfhoq13ms
Merged in pkg-config fixes.

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docs/groupby.rst
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The GROUP BY clause is used to extract only those records that fulfill a specified criterion.
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SQL GROUP BY Syntax
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.. code-block:: mysql
 
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SQL GROUP BY Syntax ::
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        SELECT column_name, aggregate_function(column_name)
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        FROM table_name
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| 6       |2011-01-03    | Food         |20           |175       |
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+---------+--------------+--------------+-------------+----------+
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Running the following simple query
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.. code-block:: mysql
 
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Running the following simple query::
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        SELECT userID
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        FROM activities
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However, GROUP BY is much more powerful when used with an aggregate function. Let's say you want to find the total amount spent by each unique User.
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You could use the following SQL statement:
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.. code-block:: mysql
 
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You could use the following SQL statement: ::
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        SELECT userID,SUM(ActivityCost) AS "Activity Total"
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        FROM Activities
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With the aggregate SUM() function, SQL can calculate how much each unique user has spent on activities over time.
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We can also use the GROUP BY statement on more than one column, like this:
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.. code-block:: mysql
 
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We can also use the GROUP BY statement on more than one column, like this: ::
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        SELECT userID,ActivityDate,SUM(ActivityCost)
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        FROM Activities