Difference between revisions of "SELECT .. GROUP BY"
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Revision as of 18:00, 22 January 2013
SELECT .. GROUP BY
Host cities and continents for the Olympics Games are stored in the table
Notice that Europe appears in the table twice:
DROP TABLE games
CREATE TABLE games( yr INTEGER, city VARCHAR(20), continent VARCHAR(20)); INSERT INTO games VALUES (2000,'Sydney','Australasia'); INSERT INTO games VALUES (2004,'Athens','Europe'); INSERT INTO games VALUES (2008,'Beijing','Asia'); INSERT INTO games VALUES (2012,'London','Europe');
In a GROUP BY statement only distinct values are shown for the column in the GROUP BY. This example shows the continents hosting the Olympics with the count of the number of games held.
SELECT continent, COUNT(yr) FROM scott.games GROUP BY continent
SELECT continent, COUNT(yr) FROM games GROUP BY continent