title: insert into statement in c#
body: <p>I want to create an SQL statement that inserts a value taken from a textBox into a column where any value in that column is NULL</p>
  
  <p>I'm doing it in C# and I was wondering if anyone could help me out...
  I wrote a pseudo code version of the command:</p>
  
  <pre><code>string newPhoneNumber = textBox.Text;
  SqlCommand cmd = new SqlCommand(
  "INSERT INTO table ([Tag ID]) 
   VALUES ('" + newPhoneNumber + "')"; 
   WHERE columnName = NULL" 
  cmd.ExecuteNonQuery();
  </code></pre>