Difference between revisions of "SELECT"

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==BBC Country Profiles==
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A SELECT statement gets data from a table. Each table contains rows and columns - you can SELECT some columns and ignore others
This tutorial introduces SQL as a query language. We will be using the SELECT command on the table bbc:
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*The column names on the select line control which columns you get
<table style='' border='1'><tr>
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*The FROM clause controls which table you access
<th>name</th>
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<div class=params>schema:scott</div>
<th>region</th>
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The table <code>games</code> shows the year and the city hosting the Olympic Games.
<th>area</th>
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<table border='1'>
<th>population</th>
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<caption>games</caption>
<th>gdp</th>
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<tr> <th>yr</th> <th>city</th> <th>y1</th></tr>
</tr>
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<tr> <td align='right'>2000</td> <td>Sydney</td> <td></td></tr>
<tr>
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<tr> <td align='right'>2004</td> <td>Athens</td> <td>2000</td></tr>
<td>Afghanistan</td>
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<tr> <td align='right'>2008</td> <td>Beijing</td><td>2004</td> </tr>
<td>South Asia</td>
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<tr> <td align='right'>2012</td> <td>London</td><td>2008</td> </tr>
<td align='right'>652225</td>
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<td align='right'>26000000</td>
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<td></td>
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</tr>
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<tr>
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<td>Albania</td>
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<td>Europe</td>
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<td align='right'>28728</td>
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<td align='right'>3200000</td>
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<td align='right'>6656000000</td>
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</tr>
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<tr>
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<td>Algeria</td>
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<td>Middle East</td>
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<td align='right'>2400000</td>
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<td align='right'>32900000</td>
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<td align='right'>75012000000</td>
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</tr>
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<tr>
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<td>Andorra</td>
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<td>Europe</td>
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<td align='right'>468</td>
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<td align='right'>64000</td>
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<td></td>
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</tr>
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<tr>
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<td colspan='5'>...</td>
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</tr>
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</table>
 
</table>
 
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<div class=qu>
==Warming up==
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The SELECT statement returns results from a <i>table</i>.
<div class='qu'>
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In this example the table is <code>games</code> and the columns are
[[Read the notes about this table.]] Observe the result of running a simple SQL command.
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<code>yr</code> and <code>city</code>.
<source lang='sql' class='def'>
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<div class=tidy>
SELECT name, region, population FROM bbc
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DROP TABLE games;
</source>
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</div>
 
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<div class=setup>
<source lang='sql' class='ans'>
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CREATE TABLE games(yr INT, city VARCHAR(20),y1 INT);
SELECT name, region, population FROM bbc
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INSERT INTO games(city,yr) VALUES ('Sydney',2000);
</source>
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INSERT INTO games(city,yr,y1) VALUES ('Athens',2004,2000);
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INSERT INTO games(city,yr,y1) VALUES ('Beijing',2008,2004);
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INSERT INTO games(city,yr,y1) VALUES ('London',2012,2008);
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</div>
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<div class=def>
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SELECT yr, city FROM games
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</div>
 
</div>
 
</div>
  
==Large Countries==
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===See also:===
<div class='qu'>
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*[[SELECT_basics | SELECT Tutorial]] - practice using the SELECT command
Show the name for the countries  that have a population of at least 200 million. (200 million is 200000000, there are eight zeros)
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*[[SELECT_.._WHERE  |SELECT ... WHERE]] - the WHERE clause allows you to get some rows but not others
<source lang='sql' class='def'>
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SELECT name FROM bbc
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WHERE population>250000000
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</source>
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<source lang='sql' class='ans'>
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SELECT name FROM bbc
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WHERE population>200000000
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</source>
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</div>
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Revision as of 08:03, 3 January 2013

A SELECT statement gets data from a table. Each table contains rows and columns - you can SELECT some columns and ignore others

  • The column names on the select line control which columns you get
  • The FROM clause controls which table you access
schema:scott

The table games shows the year and the city hosting the Olympic Games.

games
yr city y1
2000 Sydney
2004 Athens 2000
2008 Beijing2004
2012 London2008

The SELECT statement returns results from a table. In this example the table is games and the columns are yr and city.

DROP TABLE games;

CREATE TABLE games(yr INT, city VARCHAR(20),y1 INT); INSERT INTO games(city,yr) VALUES ('Sydney',2000); INSERT INTO games(city,yr,y1) VALUES ('Athens',2004,2000); INSERT INTO games(city,yr,y1) VALUES ('Beijing',2008,2004); INSERT INTO games(city,yr,y1) VALUES ('London',2012,2008);

SELECT yr, city FROM games

See also:

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