title: Getting all cell data from a specific column in a Datagridview
body: <p>Let's say the datagridview has 3 columns.
  The Datagridview is filled with data form a SQL database.
  Now i want the data of the column 'age' and write it to a list so i can use the data late but i only want the INTs. Can some please help me? a code example would be lovely. </p>
  
  <pre><code>|---------|----------|----------|
  |    id   |   name   |   age    |
  |---------|----------|----------|
  |    1    |   john   |   20     |
  |---------|----------|----------| 
  |    2    |   jane   |   21     |
  |---------|----------|----------|
  |    3    |   jack   |   22     |
  |---------|----------|----------|  
  </code></pre>