Alessandro Bonazzi 5c7aa8c1c0 Patch level : 12.0 no-patch
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Aggiunta documentazione di sqlite 3
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The generate_series Table-Valued Function
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Table Of Contents
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<div id="toc_sub"><div class="fancy-toc1"><a href="#overview">1. Overview</a></div>
<div class="fancy-toc2"><a href="#equivalent_recursive_common_table_expression">1.1. Equivalent Recursive Common Table Expression</a></div>
<div class="fancy-toc1"><a href="#usage_examples">2. Usage Examples</a></div>
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<h1 id="overview"><span>1. </span>Overview</h1>
<p>The generate_series(START,END,STEP) <a href="vtab.html#tabfunc2">table-valued function</a> is a
<a href="loadext.html">loadable extension</a> included in the SQLite source tree, and compiled into
the <a href="cli.html">command-line shell</a>. The generate_series() table has a single
result column named "value" holding integer values
and a number of rows determined by the
parameters START, END, and STEP. The first row of the table has
a value of START. Subsequent rows increase by STEP up to END.
</p><p>Omitted parameters take on default values. STEP defaults to 1.
END defaults to 9223372036854775807. START defaults to 0.
</p><h2 id="equivalent_recursive_common_table_expression"><span>1.1. </span>Equivalent Recursive Common Table Expression</h2>
<p>The generate_series table can be simulated using a
<a href="lang_with.html#recursivecte">recursive common table expression</a>. If the three parameters
are $start, $end, and $step, then the equivalent common table
expression is:
</p><div class="codeblock"><pre>WITH RECURSIVE generate_series(value) AS (
SELECT $start
UNION ALL
SELECT value+$step FROM generate_series
WHERE value+$step&lt;=$end
) ...
</pre></div>
<p>The common table expression works without having to load an
extension. On the other hand, the extension is easier to program
and faster.
</p><h1 id="usage_examples"><span>2. </span>Usage Examples</h1>
<p>Generate all multiples of 5 less than or equal to 100:
</p><div class="codeblock"><pre>SELECT value FROM generate_series(5,100,5);
</pre></div>
<p>Generate the 20 random integer values:
</p><div class="codeblock"><pre>SELECT random() FROM generate_series LIMIT 20;
</pre></div>
<p>Find the name of every customer whose account number
is an even multiple of 100 between 10000 and 20000.
</p><div class="codeblock"><pre>SELECT customer.name
FROM customer, generate_series(10000,20000,100)
WHERE customer.id=value;
/* or */
SELECT name FROM customer
WHERE id IN (SELECT value
FROM generate_series(10000,20000,200));
</pre></div>