~drizzle-trunk/drizzle/development

Group By

========

 

The GROUP BY clause is used to extract only those records that fulfill a specified criterion.

 

SQL GROUP BY Syntax ::

 

        SELECT column_name, aggregate_function(column_name)

        FROM table_name

        WHERE column_name operator value

        GROUP BY column_name

 

        

WHERE Clause Example

 

The "Activities" table:

 

+---------+--------------+-------------+----------+

|Id       |ActivityDate  |ActivityType |User      |

+=========+==============+=============+==========+

| 1       |              | Sue         |Larson    | 

+---------+--------------+-------------+----------+

| 2       | Roberts      | Teri        |Roberts   |

+---------+--------------+-------------+----------+

| 3       | Peterson     | Kari        |Peterson  | 

+---------+--------------+-------------+----------+

| 4       | Larson       | Sue         |Smith     | 

+---------+--------------+-------------+----------+

| 5       | Roberts      | Teri        |Dagwood   |

+---------+--------------+-------------+----------+

| 6       | Peterson     | Kari        |Masters   | 

+---------+--------------+-------------+----------+

 

If you want to select only the persons living in the city "Chicago" from the table above, use the following SELECT statement: ::

 

        SELECT * FROM Persons

        WHERE City='Chicago'

 

The result-set will look like this:

 

+---------+------------+----------+----------+--------+

| Id      |LastName    |FirstName |Address   |City    |

+---------+------------+----------+----------+--------+

|1        | Larson     | Sue      |3 Cherry  | Chicago|

+---------+------------+----------+----------+--------+

|2        | Roberts    | Teri     |21 Brown  | Chicago|

+---------+------------+----------+----------+--------+