title: The multi-part identifier "Table.column" could not be bound on Inner Join
body: <p>Please, help me.</p>
  
  <p>I have 2 tables: <code>MainInfo (userName, pw)</code>&amp; <code>BasicInfo (userName, birthday, phone)</code>.
  I do an query as follow:</p>
  
  <pre><code>SELECT MainInfo.userName, pw, birthday, phone
  FROM MainInfo M INNER JOIN BasicInfo B
  ON M.userName = B.userName
  </code></pre>
  
  <p>But it throw an error: <code>The multi-part identifier "MainInfo.userName" could not be bound.</code> What's wrong? I don't understand! I think about it very much, but still don't know why. Please help me!!</p>