title: Valid query to check if row exists in SQLite3
body: <p>Is this the most efficient way to check if a row exists in a table?</p>
  <pre><code>SELECT EXISTS(SELECT 1 FROM myTbl WHERE u_tag=&quot;tag&quot;);
  </code></pre>
  <p>Table is...</p>
  <pre><code>CREATE TABLE myTbl(id INT PRIMARY KEY, u_tag TEXT);
  </code></pre>
  <p>Also what is the return value for this, if the row doesn't exist? Is it false (bool) or 0 (int) or NULL?</p>