Difference between revisions of "SELECT .. SELECT"
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<h3>The Derived Table (SELECT FROM SELECT)</h3> | <h3>The Derived Table (SELECT FROM SELECT)</h3> | ||
| − | <p> | + | <p>You can use the results from one query in another query</p> |
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<div class='qu'> | <div class='qu'> | ||
You may use a SELECT statement in the FROM line. | You may use a SELECT statement in the FROM line. | ||
In this example the table is <code>beast</code> and the columns are <code>id</code> and <code>legs</code>. | In this example the table is <code>beast</code> and the columns are <code>id</code> and <code>legs</code>. | ||
<source lang='sql' class='def'> | <source lang='sql' class='def'> | ||
| − | SELECT name, | + | SELECT name, gdp_pre_capita |
| − | FROM | + | FROM |
| − | (SELECT | + | (SELECT name, gdp/population AS gdp_per_capita |
| − | FROM bbc | + | FROM bbc) X |
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</source> | </source> | ||
</div> | </div> | ||
Revision as of 23:34, 8 August 2012
The Derived Table (SELECT FROM SELECT)
You can use the results from one query in another query
You may use a SELECT statement in the FROM line.
In this example the table is beast and the columns are id and legs.
SELECT name, gdp_pre_capita FROM (SELECT name, gdp/population AS gdp_per_capita FROM bbc) X
What about ties?
If one region has two countries with the same, highest population then the query will produce the right answers but there will be duplication- both countries will be shown.
See also:
