Difference between revisions of "SELECT Reference"
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| Line 14: | Line 14: | ||
</source> | </source> | ||
</td><td> | </td><td> | ||
<table class="sqlmine"><tr><th>name</th><th>population</th></tr><tr><td>Canada</td><td class="r">32000000</td></tr | <table class="sqlmine"><tr><th>name</th><th>population</th></tr><tr><td>Canada</td><td class="r">32000000</td></tr<tr><td>United States of America</td><td class="r">295000000</td></tr></table> | ||
</td></tr></table> | </td></tr></table> | ||
*The SELECT line determines which columns to show - in this case <code>name</code> and <code>population</code>, both of which are columns of the bbc table. | *The SELECT line determines which columns to show - in this case <code>name</code> and <code>population</code>, both of which are columns of the bbc table. | ||
Revision as of 13:13, 27 February 2015
Template:S The SELECT command is used to show data from a database.
The output from a SELECT statement is always a grid - with a number of rows and a number of columns.
Simple SELECT
The simplest SELECT commands involve a single table:
| SQL | Result | ||||||
|---|---|---|---|---|---|---|---|
SELECT name, population
FROM bbc
WHERE region='North America'
|
</tr
|
- The SELECT line determines which columns to show - in this case
nameandpopulation, both of which are columns of the bbc table. - The WHERE clause determines which rows to show
- The SELECT statement may involve data from more than one table using a JOIN or a UNION.
- SELECT statements may nested - that is the output from one SELECT may be the input to another SELECT.
- The output from a SELECT may be added to another table using INSERT .. SELECT