ement
will change all of the rows that match the <tt>WHERE</tt> clause, or if 
a <tt>WHERE</tt> clause is not specified, it performs the <tt>UPDATE</tt>
on all of the rows in the table.<br />
<br />
These four basic SQL commands (INSERT, SELECT, UPDATE, and DELETE) allow 
the four basic operations needed to create and maintain data.</font><br />
<br />
<a name="toc159"></a>
<h2><font color="black"><a name="htoc174">14.6</a>&nbsp;&nbsp;Spidering Twitter using a database</font></h2>
<font color="black">In thi