title: PDO_ODBC: Data source name not found and no default driver specified
body: <p>I'm trying to access an ODBC connection in PHP via PDO_ODBC. This is my code:</p>
  
  <p><code>$db = new PDO('odbc:MyDSN', '', '');</code></p>
  
  <p>And I'm getting this error:</p>
  
  <blockquote>
    <p>SQLSTATE[IM002] SQLConnect: 0 [Microsoft][ODBC Driver Manager] Data
    source name not found and no default driver specified</p>
  </blockquote>
  
  <p>I know the DSN is working because I can use it in Python with pyodbc. The type is User DSN - does it need to be a System DSN? I'm not specifying a driver because I figured ODBC was abstracting that away, but maybe I need to? The underlying DB is Oracle, if that helps.</p>
  
  <p>Thank you!</p>