title: Using table values in DATEDIFF function
body: <p>So I am learning about TSQL and have been given an assignment to do an App that details stuff about a certain series of movies. One of the things I would like to add to the finished product is a DATEDIFF where I have the birthdate of the main actor and the Premiere date of the movie but would like to return the age of the actor at the time of the Premiere.</p>
  
  <p>My question is, HOW do I specify the dates, given a DATEDIFF statement if those dates already exist in a table?</p>
  
  <p>Examples of the tables follow.</p>
  
  <p>Bond</p>
  
  <pre><code>BondID   FirstName   LastName   Birthdate
  1        Sean        Connery    8/25/1930
  2        George      Lazenby    9/5/1939
  3        Roger       Moore      10/14/1927
  4        Timothy     Dalton     3/21/1946
  5        Pierce      Brosnan    5/16/1953
  6        Daniel      Craig      3/2/1968
  </code></pre>
  
  <p>Film</p>
  
  <pre><code>ID   BondID    FilmTitle             Premiere
  1      1       Dr. No                1963-05-08
  2      1       From Russia With Love 1974-04-08
  3      1       Goldfinger            1964-12-22
  4      1       Thunderball           1965-12-29 
  </code></pre>
  
  <p>Here is what I have presently.</p>
  
  <pre><code>SELECT b.Birthdate, f.Premiere, b.FirstName, b.LastName, f.FilmTitle
  FROM Bond b INNER JOIN FilmID  f ON b.BondID = f.BondID
  WHERE b.BondID = 1
  
  SELECT DATEDIFF(YEAR, GETDATE(), GETDATE())  AS "YearDif"
  WHERE GETDATE() = Bond.Birthdate AND GETDATE() = f.Premiere
  </code></pre>
  
  <p>Data</p>
  
  <pre><code>     Birthdate  Premiere    FirstName LastName  FilmTitle
  1    1930-08-25 1963-05-08  Sean      Connery   Dr. No
  2    1930-08-25 1974-04-08  Sean      Connery   From Russia With Love
  3    1930-08-25 1964-12-22  Sean      Connery   Goldfinger
  4    1930-08-25 1965-12-29  Sean      Connery   Thunderball
  </code></pre>
  
  <p>I would like to add a column that states the age of the actor at the time of the premiere...I think I have a handle on that one... But...</p>
  
  <p>I get that the second part of the DATEDIFF part isn't correct, but how do I tell the DATEDIFF where to get the date values?</p>
  
  <p>Any help would be wonderous!</p>