Control User Editing of Table Data, Read in From SQL Server Database

Question

Currently I have a C# application which is reading in data from a table on my SQL Server database.

This is for end user purposes and management, I want them to be able to edit that data and commit it back to the database.

private void fillDataGrid()
{
   string connectionString = "Server=; Database=; User Id=; Password=;";
   DataTable Table = new DataTable("TestTable");

   using (SqlConnection _con = new SqlConnection(connectionString))
   {
       string queryStatement = "SELECT * FROM dbo.table ORDER BY id ASC";

       using (SqlCommand _cmd = new SqlCommand(queryStatement, _con))
       {
           SqlDataAdapter _dap = new SqlDataAdapter(_cmd);

           _con.Open();
           _dap.Fill(Table);
           _con.Close();
       }
   }

   dataGridView1.DataSource = Table;
}

How do I commit the changes made through the app back to the server again?

Also, say I have a column called Colour, is there a way I could specify the possible data for each row. I.E. rather than allow the user to type 'yellow', have red, yellow and blue as 'drop - down' options?

Answer 1

To commit changes to database, you have to specify InsertCommand, UpdateCommand and DeleteCommand of the adapter first.

May be helpful:

http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqldataadapter(v=vs.90).aspx

http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqldataadapter.insertcommand(v=vs.90).aspx

http://msdn.microsoft.com/en-us/library/ms254937(v=vs.90).aspx

Also, you can use DataGridViewComboBoxColumn (Beware of the null values in your Colour column, though, it does not handle nulls well)

// choose from existng:
var data = (from a in Table.AsEnumerable()
             select new ValueHolder
             {
                 Name = a.Field<string>("Colour")
             }).Distinct().OrderBy(p => p.Name).ToList(); 
// your own
var data = new List<ValueHolder>();
data.Add(new ValueHolder("Red"));
data.Add(new ValueHolder("Yellow"));
//..................

var column = new DataGridViewComboBoxColumn();      
column.DataSource = data; 
column.ValueMember = "Name"; 
column.DisplayMember = "Name"; 

dataGridView1.Columns.Add(column); 

//------------------------------------------------------------

class ValueHolder
{
  public string Name{get;set;}

   public ValueHolder(string name)
   {
     this.Name = name;
   }

  // this part may not be necessary without nulls:
  //public override bool Equals(object obj)
  //      {
  //          ValueHolder other = obj as ValueHolder;
  //          if (other.Name.Equals(this.Name)) return true;
  //          return false;
  //      }

  //      public override int GetHashCode()
  //      {
  //          return Name == null ? 0 : Name.GetHashCode();
  //      } 
}

it probably can be done in a simpler way, though.