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<title>2.8.Updates</title>
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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="tutorial-update"></a>2.8.Updates</h2></div></div></div>
<a name="id569482"></a><p> You can update existing rows using the
<code class="command">UPDATE</code> command.
Suppose you discover the temperature readings are
all off by 2 degrees as of November 28. You may update the
data as follows:
</p>
<pre class="programlisting">UPDATE weather
SET temp_hi = temp_hi - 2, temp_lo = temp_lo - 2
WHERE date > '1994-11-28';</pre>
<p>
</p>
<p> Look at the new state of the data:
</p>
<pre class="programlisting">SELECT * FROM weather;
city | temp_lo | temp_hi | prcp | date
---------------+---------+---------+------+------------
San Francisco | 46 | 50 | 0.25 | 1994-11-27
San Francisco | 41 | 55 | 0 | 1994-11-29
Hayward | 35 | 52 | | 1994-11-29
(3 rows)</pre>
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