vb.net - How to convert an string to a Char(20) sql datatype -

I try to insert a string into a char (20) column in my SQL server database I am doing .

I set the string to be equal to one value and then add it to a parameter

  thisstring = "1914" cmd.Parameters.AddWithValue (" @ Code ", this string)   
 Although every time I try, it ends up looking like this in the database  
   
 I like this like  1913, 000000, 000001 .  
  This string = thisstring.PadLeft (20, "")  
 When I try to string string with this string  
  > 
 or  
  thisstring = "" & Amp; The string   
 I am getting  
 
 string or binary data will be minimized   
 even if the field  
 
 
 
  
 
 
 
 > 
 
 I'm not sure at all, but I think the problem is in AddWithValue. 
 While convenient, this method does not allow specifying the exact datatype to pass the database engine nor the size of the parameter. It always passes a nvarchar parameter for the C #Unicode string.  
 I think the standard parameter  
  dim p = new SqlParameter ("@ code", SqlDbType.Char, 20) p.Value = thisstring.PadLeft (20 , "")