@@ -107,4 +107,4 @@ GROUP BY location, type </code></pre>
FROM thermometer
WHERE name<>'beijing' and ts>=now-1d
INTERVAL(10M)
GROUP BY location, type</code></pre><ahref='../index.html'>回去</a></section></main></div><?php include($s.'/footer.php'); ?><script>$('pre').addClass('prettyprint linenums');PR.prettyPrint()</script><script src='lib/docs/liner.js'></script></body></html>
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GROUP BY location, type</code></pre><ahref='../index.html'>回去</a></section></main></div><?php include($s.'/footer.php'); ?><script>$('pre').addClass('prettyprint linenums');PR.prettyPrint()</script><script src='lib/docs/liner.js'></script></body></html>
<p>It changes the name of a tag from old to new. </p>
<aclass='anchor'id='Change-the-Tag's-Value'></a><h3>Change the Tag's Value</h3>
<pre><codeclass="mysql language-mysql">ALTER TABLE <table_name> SET TAG <tag_name>=<new_tag_value></code></pre>
<p>It changes a table's tag value to a new one. </p><ahref='../index.html'>Back</a></section></main></div><?php include($s.'/footer.php'); ?><script>$('pre').addClass('prettyprint linenums');PR.prettyPrint()</script><script src='lib/docs/liner.js'></script></body></html>
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<p>It changes a table's tag value to a new one. </p><ahref='../index.html'>Back</a></section></main></div><?php include($s.'/footer.php'); ?><script>$('pre').addClass('prettyprint linenums');PR.prettyPrint()</script><script src='lib/docs/liner.js'></script></body></html>
"One Table for One Device" design can improve the insert/query performance significantly for a single device. But it has a side effect, the aggregation of multiple tables becomes hard. To reduce the complexity and improve the efficiency, TDengine introduced a new concept: STable (Super Table).