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Bruce Momjian
23 years ago
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$Header: /cvsroot/pgsql/doc/src/sgml/Attic/libpgeasy.sgml,v 2.9 2002/03/04 18:50:20 momjian Exp $ |
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<chapter id="pgeasy"> |
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<title><application>libpgeasy</application> - Simplified C Library</title> |
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<note> |
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<title>Author</title> |
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<para> |
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Written by Bruce Momjian |
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(<email>pgman@candle.pha.pa.us</email>) |
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and last updated 2002-03-04 |
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</para> |
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</note> |
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<para> |
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<application>pgeasy</application> allows you to cleanly interface |
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to the <application>libpq</application> library, more like a 4GL |
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SQL interface. Refer to <xref linkend="libpq"> for more |
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information about <application>libpq</application>. |
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</para> |
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<para> |
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It consists of a set of simplified C functions that encapsulate the |
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functionality of <application>libpq</application>. The functions are: |
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<itemizedlist> |
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<listitem> |
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<synopsis> |
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PGresult *doquery(char *query); |
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</synopsis> |
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</listitem> |
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<listitem> |
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<synopsis> |
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PGconn *connectdb(char *options); |
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</synopsis> |
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</listitem> |
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<listitem> |
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<synopsis> |
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void disconnectdb(); |
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</synopsis> |
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</listitem> |
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<listitem> |
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<synopsis> |
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int fetch(void *param,...); |
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</synopsis> |
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</listitem> |
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<listitem> |
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<synopsis> |
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int fetchwithnulls(void *param,...); |
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</synopsis> |
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</listitem> |
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<listitem> |
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<synopsis> |
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void reset_fetch(); |
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</synopsis> |
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</listitem> |
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<listitem> |
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<synopsis> |
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void on_error_continue(); |
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</synopsis> |
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</listitem> |
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<listitem> |
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<synopsis> |
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void on_error_stop(); |
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</synopsis> |
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</listitem> |
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<listitem> |
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<synopsis> |
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PGresult *get_result(); |
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</synopsis> |
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</listitem> |
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<listitem> |
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<synopsis> |
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void set_result(PGresult *newres); |
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</synopsis> |
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</listitem> |
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</itemizedlist> |
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</para> |
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<para> |
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Many functions return a structure or value, so you can work |
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with the result if required. |
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</para> |
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<para> |
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You basically connect to the database with |
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<function>connectdb</function>, issue your query with |
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<function>doquery</function>, fetch the results with |
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<function>fetch</function>, and finish with |
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<function>disconnectdb</function>. |
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</para> |
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<para> |
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For <literal>SELECT</literal> queries, <function>fetch</function> |
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allows you to pass pointers as parameters, and on return the |
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variables are filled with data from the binary cursor you opened. |
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These binary cursors cannot be used if you are running the |
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<application>pgeasy</application> client on a system with a different |
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architecture than the database server. If you pass a NULL pointer |
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parameter, the column is skipped. <function>fetchwithnulls</function> |
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allows you to retrieve the NULL status of the field by passing an |
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<literal>int*</literal> after each result pointer, which returns true |
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or false to indicate if the field is null. You can always use |
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<application>libpq</application> functions on the |
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<structname>PGresult</structname> pointer returned by |
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<function>doquery</function>. <function>reset_fetch</function> starts |
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the fetch back at the beginning. |
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</para> |
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<para> |
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<function>get_result</function> and <function>set_result</function> |
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allow you to handle multiple open result sets. Use |
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<function>get_result</function> to save a result into an application |
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variable. You can then later use <function>set_result</function> to |
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return to the previously save result. |
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</para> |
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<para> |
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There are several demonstration programs in |
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<filename>pgsql/src/interfaces/libpgeasy/examples</>. |
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</para> |
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</chapter> |
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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:nil |
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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:"./reference.ced" |
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sgml-exposed-tags:nil |
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sgml-local-catalogs:("/usr/lib/sgml/catalog") |
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sgml-local-ecat-files:nil |
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End: |
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--> |
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