Difference between revisions of "SELECT"

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*The FROM clause controls which table you access
 
*The FROM clause controls which table you access
 
The table <code>games</code> shows the year and the city hosting the Olympic Games.
 
The table <code>games</code> shows the year and the city hosting the Olympic Games.
 +
<table border='1'>
 +
<caption>games</caption>
 +
<tr> <th>AUTHOR_ID</th> <th>NAME</th> </tr>
 +
<tr> <td align='right'>1</td> <td>Shevchenko</td>  </tr>
 +
<tr> <td align='right'>2</td> <td>Franko</td></tr>
 +
<tr> <td align='right'>3</td> <td>Lesya</td> </tr>
 +
<tr> <td align='right'>4</td> <td>Nestaiko</td> </tr>
 +
<tr> <td align='right'>5</td> <td>Tychyna</td></tr>
 +
</table>
 
<table border='1'>
 
<table border='1'>
 
<caption>games</caption>
 
<caption>games</caption>

Revision as of 14:49, 25 May 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
AUTHOR_ID NAME
1 Shevchenko
2 Franko
3 Lesya
4 Nestaiko
5 Tychyna
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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