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https://github.com/sigmasternchen/php-doc-en
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git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@297028 c90b9560-bf6c-de11-be94-00142212c4b1
128 lines
4.3 KiB
XML
128 lines
4.3 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<refentry xml:id="function.sqlite-popen" xmlns="http://docbook.org/ns/docbook">
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<refnamediv>
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<refname>sqlite_popen</refname>
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<refpurpose>
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Opens a persistent handle to an SQLite database and create the database if it does not exist
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</refpurpose>
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</refnamediv>
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<refsect1 role="description">
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&reftitle.description;
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<methodsynopsis>
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<type>resource</type><methodname>sqlite_popen</methodname>
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<methodparam><type>string</type><parameter>filename</parameter></methodparam>
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<methodparam choice="opt"><type>int</type><parameter>mode</parameter><initializer>0666</initializer></methodparam>
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<methodparam choice="opt"><type>string</type><parameter role="reference">error_message</parameter></methodparam>
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</methodsynopsis>
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<simpara>
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This function behaves identically to <function>sqlite_open</function>
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except that is uses the persistent resource mechanism of PHP.
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For information about the meaning of the parameters, read the
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<function>sqlite_open</function> manual page.
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</simpara>
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<para>
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<function>sqlite_popen</function> will first check to see if a persistent
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handle has already been opened for the given
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<parameter>filename</parameter>. If it finds one, it returns that handle
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to your script, otherwise it opens a fresh handle to the database.
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</para>
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<para>
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The benefit of this approach is that you don't incur the performance
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cost of re-reading the database and index schema on each page hit served
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by persistent web server SAPI's (any SAPI except for regular CGI or CLI).
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</para>
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<note>
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<simpara>
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If you use persistent handles and have the database updated by a
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background process (perhaps via a crontab), and that process re-creates
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the database by overwriting it (either by unlinking and rebuilding, or
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moving the updated version to replace the current version),
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you may experience undefined behaviour when a persistent handle on the
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old version of the database is recycled.
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</simpara>
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<simpara>
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To avoid this situation, have your background processes open the same
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database file and perform their updates in a transaction.
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</simpara>
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</note>
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</refsect1>
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<refsect1 role="parameters">
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&reftitle.parameters;
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<para>
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<variablelist>
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<varlistentry>
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<term><parameter>filename</parameter></term>
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<listitem>
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<para>
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The filename of the SQLite database. If the file does not exist, SQLite
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will attempt to create it. PHP must have write permissions to the file
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if data is inserted, the database schema is modified or to create the
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database if it does not exist.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>mode</parameter></term>
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<listitem>
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<para>
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The mode of the file. Intended to be used to open the database in
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read-only mode. Presently, this parameter is ignored by the sqlite
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library. The default value for mode is the octal value
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<literal>0666</literal> and this is the recommended value.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>error_message</parameter></term>
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<listitem>
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<para>
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Passed by reference and is set to hold a descriptive error message
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explaining why the database could not be opened if there was an error.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect1>
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<refsect1 role="returnvalues">
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&reftitle.returnvalues;
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<para>
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Returns a resource (database handle) on success, &false; on error.
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</para>
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</refsect1>
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<refsect1 role="seealso">
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&reftitle.seealso;
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<para>
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<simplelist>
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<member><function>sqlite_open</function></member>
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<member><function>sqlite_close</function></member>
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<member><function>sqlite_factory</function></member>
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</simplelist>
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</para>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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sgml-parent-document:nil
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sgml-default-dtd-file:"~/.phpdoc/manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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