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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The table <code>games</code> shows the year and the city hosting the Olympic Games.
<th>region</th>
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<table border='1'>
<th>area</th>
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<caption>games</caption>
<th>population</th>
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<tr> <th>yr</th> <th>city</th> <th>y1</th></tr>
<th>gdp</th>
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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>
<tr>
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<tr> <td align='right'>2008</td> <td>Beijing</td><td>2004</td> </tr>
<td>Afghanistan</td>
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<tr> <td align='right'>2012</td> <td>London</td><td>2008</td> </tr>
<td>South Asia</td>
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<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>
==Exercises==
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<div class=qu>
Using the <code>SELECT</code> statement.
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The SELECT statement returns results from a <i>table</i>.
 
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In this example the table is <code>games</code> and the columns are
<div class='qu'>
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<code>yr</code> and <code>city</code>.
[[Read the notes about this table.]]
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<div class=tidy>
Issue the command:
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DROP TABLE games;
SELECT name, region, population FROM bbc
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Look at the output.
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<source lang='sql'>
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SELECT name, region, population FROM bbc
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</source>
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<source lang='sql'>
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SELECT name, region, population FROM bbc
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</source>
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</div>
 
</div>
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<div class=setup>
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CREATE TABLE games(yr INT, city VARCHAR(20),y1 INT);
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INSERT INTO games(city,yr) VALUES ('Sydney',2000);
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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>
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</div>
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===See also:===
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*[[SELECT_basics | SELECT Tutorial]] - practice using the SELECT command
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*[[SELECT_.._WHERE  |SELECT ... WHERE]] - the WHERE clause allows you to get some rows but not others

Revision as of 17:59, 22 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

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

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