SQL Count Query with Grouping by multiple Columns

Posted by Christian on Stack Overflow See other posts from Stack Overflow or by Christian
Published on 2010-04-21T09:53:21Z Indexed on 2010/04/21 11:23 UTC
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I have a table with three filled columns named "Name", "City" and "Occupation". I want to create a new column in the same table that contains the number of people who have the same occupation.

"Name" | "City" | "Occupation"
------------------------------
Amy    | Berlin | Plumber
Bob    | Berlin | Plumber
Carol  | Berlin | Lawyer
David  | London | Plumber

I want to have a table that contains:

"Name" | "City" | "Occupation" | "Number"
---------------------------------------
Amy    | Berlin | Plumber      | 2
Bob    | Berlin | Plumber      | 2
Carol  | Berlin | Lawyer       | 1
David  | London | Plumber      | 1

How does the SQL Query that creates the new columns have to look like? I want to actually create a new column in the database that I can access later.

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