mirror of https://github.com/postgres/postgres
Thomas G. Lockhart
26 years ago
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$Header: /cvsroot/pgsql/doc/src/sgml/Attic/libpgeasy.sgml,v 2.1 2000/03/31 03:26:21 thomas Exp $ |
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--> |
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<chapter id="pgeasy-chapter"> |
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<title id="pgeasy">libpgeasy - Simplified C Binding 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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(<ulink url="mailto:root@candle.pha.pa.us">root@candle.pha.pa.us</ulink>) |
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and last updated 2000-03-30. |
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</para> |
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</note> |
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<para> |
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<productname>pgeasy</productname> allows you to cleanly interface |
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to the <productname>libpq</productname> library, |
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more like a 4GL SQL interface. |
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</para> |
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<para> |
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It consists of set of simplified C functions that encapsulate the |
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functionality of libpq. |
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The functions are: |
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<itemizedlist> |
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<listitem> |
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<para> |
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PGresult *doquery(char *query); |
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</para> |
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</listitem> |
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<listitem> |
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<para> |
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PGconn *connectdb(); |
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</para> |
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</listitem> |
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<listitem> |
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<para> |
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void disconnectdb(); |
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</para> |
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</listitem> |
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<listitem> |
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<para> |
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int fetch(void *param,...); |
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</para> |
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</listitem> |
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<listitem> |
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<para> |
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int fetchwithnulls(void *param,...); |
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</para> |
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</listitem> |
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<listitem> |
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<para> |
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void reset_fetch(); |
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</para> |
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</listitem> |
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<listitem> |
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<para> |
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void on_error_continue(); |
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</para> |
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</listitem> |
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<listitem> |
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<para> |
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void on_error_stop(); |
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</para> |
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</listitem> |
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<listitem> |
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<para> |
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PGresult *get_result(); |
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</para> |
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</listitem> |
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<listitem> |
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<para> |
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void set_result(PGresult *newres); |
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</para> |
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</listitem> |
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<listitem> |
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<para> |
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void unset_result(PGresult *oldres); |
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</para> |
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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 do more 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 <function>connectdb</function>, |
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issue your query with <function>doquery</function>, |
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fetch the results with <function>fetch</function>, |
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and finish with <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 variables |
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are filled with data from the binary cursor you opened. These binary |
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cursors can not be used if you are running the |
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<productname>pgeasy</productname> |
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client on a system with a different architecture than the database |
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server. If you pass a NULL pointer parameter, the column is skipped. |
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<function>fetchwithnulls</function> allows you to retrieve the NULL |
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status of the field by passing an <literal>int*</literal> |
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after each result pointer, which returns true or false if the field is null. |
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You can always use libpq functions on the PGresult pointer returned |
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by <function>doquery</function>. |
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<function>reset_fetch</function> starts the fetch back at the beginning. |
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</para> |
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<para> |
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<function>get_result</function>, |
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<function>set_result</function>, |
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and |
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<function>unset_result</function> |
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allow you to handle multiple result sets at the same time. |
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</para> |
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<para> |
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There are a variety of demonstration programs in the |
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source directory. |
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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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