title: Combine date and time when date is a DateTime and time is a string
body: <p>I am working with an old mysql database in which a date is stored (without a time) as a datetime and a time is stored as a string (without a date).</p>
  
  <p>In C# I then have a DateTime with a value like <code>2010-06-25 12:00:00 AM</code> and a String with a value like <code>15:02</code>.</p>
  
  <p>What is the most concise way to combine these without a lot of overhead?</p>
  
  <p>I have tried a few methods including:</p>
  
  <pre><code>DateTime NewDateTime = DateTime.Parse(OldDateTime.ToString("yyyy-MM-dd ") + TimeString);
  </code></pre>
  
  <p>I dislike converting the existing DateTime to a string and appending the time.</p>
  
  <p>I can convert the time string to a date, but then I get today's date and adding it as a number of ticks to the old datetime is incorrect.</p>
  
  <p><em>Note: Don't worry about validation, it is done elsewhere. The time is represented using 24-hour format without seconds.</em></p>