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   2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>34.10. Processing Embedded SQL Programs</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="ecpg-preproc.html" title="34.9. Preprocessor Directives" /><link rel="next" href="ecpg-library.html" title="34.11. Library Functions" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">34.10. Processing Embedded SQL Programs</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="ecpg-preproc.html" title="34.9. Preprocessor Directives">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="ecpg.html" title="Chapter 34. ECPG — Embedded SQL in C">Up</a></td><th width="60%" align="center">Chapter 34. <span class="application">ECPG</span> — Embedded <acronym class="acronym">SQL</acronym> in C</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 18.0 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="ecpg-library.html" title="34.11. Library Functions">Next</a></td></tr></table><hr /></div><div class="sect1" id="ECPG-PROCESS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">34.10. Processing Embedded SQL Programs <a href="#ECPG-PROCESS" class="id_link">#</a></h2></div></div></div><p>
   3    Now that you have an idea how to form embedded SQL C programs, you
   4    probably want to know how to compile them.  Before compiling you
   5    run the file through the embedded <acronym class="acronym">SQL</acronym>
   6    <acronym class="acronym">C</acronym> preprocessor, which converts the
   7    <acronym class="acronym">SQL</acronym> statements you used to special function
   8    calls.  After compiling, you must link with a special library that
   9    contains the needed functions. These functions fetch information
  10    from the arguments, perform the <acronym class="acronym">SQL</acronym> command using
  11    the <span class="application">libpq</span> interface, and put the result
  12    in the arguments specified for output.
  13   </p><p>
  14    The preprocessor program is called <code class="filename">ecpg</code> and is
  15    included in a normal <span class="productname">PostgreSQL</span> installation.
  16    Embedded SQL programs are typically named with an extension
  17    <code class="filename">.pgc</code>.  If you have a program file called
  18    <code class="filename">prog1.pgc</code>, you can preprocess it by simply
  19    calling:
  20 </p><pre class="programlisting">
  21 ecpg prog1.pgc
  22 </pre><p>
  23    This will create a file called <code class="filename">prog1.c</code>.  If
  24    your input files do not follow the suggested naming pattern, you
  25    can specify the output file explicitly using the
  26    <code class="option">-o</code> option.
  27   </p><p>
  28    The preprocessed file can be compiled normally, for example:
  29 </p><pre class="programlisting">
  30 cc -c prog1.c
  31 </pre><p>
  32    The generated C source files include header files from the
  33    <span class="productname">PostgreSQL</span> installation, so if you installed
  34    <span class="productname">PostgreSQL</span> in a location that is not searched by
  35    default, you have to add an option such as
  36    <code class="literal">-I/usr/local/pgsql/include</code> to the compilation
  37    command line.
  38   </p><p>
  39    To link an embedded SQL program, you need to include the
  40    <code class="filename">libecpg</code> library, like so:
  41 </p><pre class="programlisting">
  42 cc -o myprog prog1.o prog2.o ... -lecpg
  43 </pre><p>
  44    Again, you might have to add an option like
  45    <code class="literal">-L/usr/local/pgsql/lib</code> to that command line.
  46   </p><p>
  47    You can
  48    use <code class="command">pg_config</code><a id="id-1.7.5.16.6.2" class="indexterm"></a>
  49    or <code class="command">pkg-config</code><a id="id-1.7.5.16.6.4" class="indexterm"></a> with package name <code class="literal">libecpg</code> to
  50    get the paths for your installation.
  51   </p><p>
  52    If you manage the build process of a larger project using
  53    <span class="application">make</span>, it might be convenient to include
  54    the following implicit rule to your makefiles:
  55 </p><pre class="programlisting">
  56 ECPG = ecpg
  57
  58 %.c: %.pgc
  59         $(ECPG) $&lt;
  60 </pre><p>
  61   </p><p>
  62    The complete syntax of the <code class="command">ecpg</code> command is
  63    detailed in <a class="xref" href="app-ecpg.html" title="ecpg"><span class="refentrytitle"><span class="application">ecpg</span></span></a>.
  64   </p><p>
  65    The <span class="application">ecpg</span> library is thread-safe by
  66    default.  However, you might need to use some threading
  67    command-line options to compile your client code.
  68   </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ecpg-preproc.html" title="34.9. Preprocessor Directives">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ecpg.html" title="Chapter 34. ECPG — Embedded SQL in C">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ecpg-library.html" title="34.11. Library Functions">Next</a></td></tr><tr><td width="40%" align="left" valign="top">34.9. Preprocessor Directives </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 18.0 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 34.11. Library Functions</td></tr></table></div></body></html>