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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-13 13:44:03 +0000 |
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| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-13 13:44:03 +0000 |
| commit | 293913568e6a7a86fd1479e1cff8e2ecb58d6568 (patch) | |
| tree | fc3b469a3ec5ab71b36ea97cc7aaddb838423a0c /doc/src/sgml/html/ecpg-concept.html | |
| parent | Initial commit. (diff) | |
| download | postgresql-16-293913568e6a7a86fd1479e1cff8e2ecb58d6568.tar.xz postgresql-16-293913568e6a7a86fd1479e1cff8e2ecb58d6568.zip | |
Adding upstream version 16.2.upstream/16.2
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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| -rw-r--r-- | doc/src/sgml/html/ecpg-concept.html | 52 |
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diff --git a/doc/src/sgml/html/ecpg-concept.html b/doc/src/sgml/html/ecpg-concept.html new file mode 100644 index 0000000..9f4854e --- /dev/null +++ b/doc/src/sgml/html/ecpg-concept.html @@ -0,0 +1,52 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!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>36.1. The Concept</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.html" title="Chapter 36. ECPG — Embedded SQL in C" /><link rel="next" href="ecpg-connect.html" title="36.2. Managing Database Connections" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">36.1. The Concept</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="ecpg.html" title="Chapter 36. ECPG — Embedded SQL in C">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="ecpg.html" title="Chapter 36. ECPG — Embedded SQL in C">Up</a></td><th width="60%" align="center">Chapter 36. <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 16.2 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="ecpg-connect.html" title="36.2. Managing Database Connections">Next</a></td></tr></table><hr /></div><div class="sect1" id="ECPG-CONCEPT"><div class="titlepage"><div><div><h2 class="title" style="clear: both">36.1. The Concept <a href="#ECPG-CONCEPT" class="id_link">#</a></h2></div></div></div><p> + An embedded SQL program consists of code written in an ordinary + programming language, in this case C, mixed with SQL commands in + specially marked sections. To build the program, the source code (<code class="filename">*.pgc</code>) + is first passed through the embedded SQL preprocessor, which converts it + to an ordinary C program (<code class="filename">*.c</code>), and afterwards it can be processed by a C + compiler. (For details about the compiling and linking see <a class="xref" href="ecpg-process.html" title="36.10. Processing Embedded SQL Programs">Section 36.10</a>.) + Converted ECPG applications call functions in the libpq library + through the embedded SQL library (ecpglib), and communicate with + the PostgreSQL server using the normal frontend-backend protocol. + </p><p> + Embedded <acronym class="acronym">SQL</acronym> has advantages over other methods + for handling <acronym class="acronym">SQL</acronym> commands from C code. First, it + takes care of the tedious passing of information to and from + variables in your <acronym class="acronym">C</acronym> program. Second, the SQL + code in the program is checked at build time for syntactical + correctness. Third, embedded <acronym class="acronym">SQL</acronym> in C is + specified in the <acronym class="acronym">SQL</acronym> standard and supported by + many other <acronym class="acronym">SQL</acronym> database systems. The + <span class="productname">PostgreSQL</span> implementation is designed to match this + standard as much as possible, and it is usually possible to port + embedded <acronym class="acronym">SQL</acronym> programs written for other SQL + databases to <span class="productname">PostgreSQL</span> with relative + ease. + </p><p> + As already stated, programs written for the embedded + <acronym class="acronym">SQL</acronym> interface are normal C programs with special + code inserted to perform database-related actions. This special + code always has the form: +</p><pre class="programlisting"> +EXEC SQL ...; +</pre><p> + These statements syntactically take the place of a C statement. + Depending on the particular statement, they can appear at the + global level or within a function. + </p><p> + Embedded + <acronym class="acronym">SQL</acronym> statements follow the case-sensitivity rules of + normal <acronym class="acronym">SQL</acronym> code, and not those of C. Also they allow nested + C-style comments as per the SQL standard. The C part of the + program, however, follows the C standard of not accepting nested comments. + Embedded <acronym class="acronym">SQL</acronym> statements likewise use SQL rules, not + C rules, for parsing quoted strings and identifiers. + (See <a class="xref" href="sql-syntax-lexical.html#SQL-SYNTAX-STRINGS" title="4.1.2.1. String Constants">Section 4.1.2.1</a> and + <a class="xref" href="sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS" title="4.1.1. Identifiers and Key Words">Section 4.1.1</a> respectively. Note that + ECPG assumes that <code class="varname">standard_conforming_strings</code> + is <code class="literal">on</code>.) + Of course, the C part of the program follows C quoting rules. + </p><p> + The following sections explain all the embedded SQL statements. + </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ecpg.html" title="Chapter 36. ECPG — Embedded SQL in C">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ecpg.html" title="Chapter 36. ECPG — Embedded SQL in C">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ecpg-connect.html" title="36.2. Managing Database Connections">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 36. <span class="application">ECPG</span> — Embedded <acronym class="acronym">SQL</acronym> in C </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16.2 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 36.2. Managing Database Connections</td></tr></table></div></body></html>
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