title: Convert DateTime with NULL value
body: <p>I am running this query</p>
  
  <pre><code>select * from dbo.CHARGES  m
  LEFT JOIN Docs z ON z.DocId=m.DocId
  AND CHARGE_DATE=CAST(z.DocDate + z.DocTime AS DATETIME)
  </code></pre>
  
  <p>And getting <code>Conversion failed when converting date and/or time from character string</code>, since some rows of <code>DocDate, DocTime</code> have null value</p>
  
  <p>Here <code>DocTime</code> is Varchar(5)</p>
  
  <p><em><strong>How can i run this query by ignoring NULL or wrong values?</em></strong></p>