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<HTML
><HEAD
><TITLE
>libpgeasy - Simplified C Library</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.64
"><LINK
REV="MADE"
HREF="mailto:pgsql-docs@postgresql.org"><LINK
REL="STYLESHEET"
TYPE="text/css"
HREF="stylesheet.css"><META
NAME="creation"
CONTENT="2002-11-26T22:36:16"></HEAD
><BODY
CLASS="CHAPTER"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="CHAPTER"
><H1
><A
NAME="pgeasy"
>Chapter 1. <SPAN
CLASS="APPLICATION"
>libpgeasy</SPAN
> - Simplified C Library</A
></H1
>
<DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
>
<P
><B
>Author: </B
> Written by Bruce Momjian
(<TT
CLASS="EMAIL"
><<A
HREF="mailto:pgman@candle.pha.pa.us"
>pgman@candle.pha.pa.us</A
>></TT
>)
and last updated 2002-03-04
</P
>
</BLOCKQUOTE
></DIV
>
<P
> <SPAN
CLASS="APPLICATION"
>pgeasy</SPAN
> allows you to cleanly interface
to the <SPAN
CLASS="APPLICATION"
>libpq</SPAN
> library, more like a 4GL
SQL interface. Refer to libpq for more
information about <SPAN
CLASS="APPLICATION"
>libpq</SPAN
>.
</P
>
<P
> It consists of a set of simplified C functions that encapsulate the
functionality of <SPAN
CLASS="APPLICATION"
>libpq</SPAN
>. The functions are:
<P
></P
></P><UL
><LI
><PRE
CLASS="SYNOPSIS"
>PGresult *doquery(char *query);</PRE
>
</LI
><LI
><PRE
CLASS="SYNOPSIS"
>PGconn *connectdb(char *options);</PRE
>
</LI
><LI
><PRE
CLASS="SYNOPSIS"
>void disconnectdb();</PRE
>
</LI
><LI
><PRE
CLASS="SYNOPSIS"
>int fetch(void *param,...);</PRE
>
</LI
><LI
><PRE
CLASS="SYNOPSIS"
>int fetchwithnulls(void *param,...);</PRE
>
</LI
><LI
><PRE
CLASS="SYNOPSIS"
>void reset_fetch();</PRE
>
</LI
><LI
><PRE
CLASS="SYNOPSIS"
>void on_error_continue();</PRE
>
</LI
><LI
><PRE
CLASS="SYNOPSIS"
>void on_error_stop();</PRE
>
</LI
><LI
><PRE
CLASS="SYNOPSIS"
>PGresult *get_result();</PRE
>
</LI
><LI
><PRE
CLASS="SYNOPSIS"
>void set_result(PGresult *newres);</PRE
>
</LI
></UL
><P>
</P
>
<P
> Many functions return a structure or value, so you can work
with the result if required.
</P
>
<P
> You basically connect to the database with
<TT
CLASS="FUNCTION"
>connectdb</TT
>, issue your query with
<TT
CLASS="FUNCTION"
>doquery</TT
>, fetch the results with
<TT
CLASS="FUNCTION"
>fetch</TT
>, and finish with
<TT
CLASS="FUNCTION"
>disconnectdb</TT
>.
</P
>
<P
> For <TT
CLASS="LITERAL"
>SELECT</TT
> queries, <TT
CLASS="FUNCTION"
>fetch</TT
>
allows you to pass pointers as parameters, and on return the
variables are filled with data from the binary cursor you opened.
These binary cursors cannot be used if you are running the
<SPAN
CLASS="APPLICATION"
>pgeasy</SPAN
> client on a system with a different
architecture than the database server. If you pass a NULL pointer
parameter, the column is skipped. <TT
CLASS="FUNCTION"
>fetchwithnulls</TT
>
allows you to retrieve the NULL status of the field by passing an
<TT
CLASS="LITERAL"
>int*</TT
> after each result pointer, which returns true
or false to indicate if the field is null. You can always use
<SPAN
CLASS="APPLICATION"
>libpq</SPAN
> functions on the
<TT
CLASS="STRUCTNAME"
>PGresult</TT
> pointer returned by
<TT
CLASS="FUNCTION"
>doquery</TT
>. <TT
CLASS="FUNCTION"
>reset_fetch</TT
> starts
the fetch back at the beginning.
</P
>
<P
> <TT
CLASS="FUNCTION"
>get_result</TT
> and <TT
CLASS="FUNCTION"
>set_result</TT
>
allow you to handle multiple open result sets. Use
<TT
CLASS="FUNCTION"
>get_result</TT
> to save a result into an application
variable. You can then later use <TT
CLASS="FUNCTION"
>set_result</TT
> to
return to the previously save result.
</P
>
<P
> There are several demonstration programs in
<TT
CLASS="FILENAME"
>/examples</TT
>.
</P
>
</DIV
></BODY
></HTML
>
|
