title: ORA-12704: character set mismatch with nvarchar2 datatype in Oracle
body: <p>I get the error code <code>ORA-12704</code> with the following query:</p>
  
  <pre><code>SELECT COALESCE(BankDetails.description,'') as description FROM BankDetails
  </code></pre>
  
  <p>The datatype of description column nvarchar2. I'm assuming the  <code>''</code> is the cause of the issue as this is not matching with the datatype.</p>