begriffs open source - ai-pg/blob - full-docs/html/tutorial-update.html

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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>2.8. Updates</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="tutorial-agg.html" title="2.7. Aggregate Functions" /><link rel="next" href="tutorial-delete.html" title="2.9. Deletions" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">2.8. Updates</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="tutorial-agg.html" title="2.7. Aggregate Functions">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="tutorial-sql.html" title="Chapter 2. The SQL Language">Up</a></td><th width="60%" align="center">Chapter 2. The <acronym class="acronym">SQL</acronym> Language</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="tutorial-delete.html" title="2.9. Deletions">Next</a></td></tr></table><hr /></div><div class="sect1" id="TUTORIAL-UPDATE"><div class="titlepage"><div><div><h2 class="title" style="clear: both">2.8. Updates <a href="#TUTORIAL-UPDATE" class="id_link">#</a></h2></div></div></div><a id="id-1.4.4.9.2" class="indexterm"></a><p>
   3     You can update existing rows using the
   4     <code class="command">UPDATE</code> command.
   5     Suppose you discover the temperature readings are
   6     all off by 2 degrees after November 28.  You can correct the
   7     data as follows:
   8
   9 </p><pre class="programlisting">
  10 UPDATE weather
  11     SET temp_hi = temp_hi - 2,  temp_lo = temp_lo - 2
  12     WHERE date &gt; '1994-11-28';
  13 </pre><p>
  14    </p><p>
  15     Look at the new state of the data:
  16 </p><pre class="programlisting">
  17 SELECT * FROM weather;
  18
  19      city      | temp_lo | temp_hi | prcp |    date
  20 ---------------+---------+---------+------+------------
  21  San Francisco |      46 |      50 | 0.25 | 1994-11-27
  22  San Francisco |      41 |      55 |    0 | 1994-11-29
  23  Hayward       |      35 |      52 |      | 1994-11-29
  24 (3 rows)
  25 </pre><p>
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