Important Facts about datagridview

Introduction

We use datagridview to display information in a customizable grid. This is about how to populate datagridview with data and how to get data to a data table from datagridview and some important facts about datagridview.

Database to DataGridView

First, create a new Windows Forms Application. Then, go to ToolBox data section and drag DataGridView control on to the Windows Form. Then let's see how to populate datagridview from database.

To do that, first create a SqlConnection object and then write a SQL command to get data from the database.

 try
   {
      //Creating SqlConnection object
      SqlConnection con = new SqlConnection();
      //setting the connection string
      con.ConnectionString = @"Data Source=|DataDirectory|\data.sdf";
      //open the connection
      con.Open();
   }
catch (Exception a)
   {
      MessageBox.Show("Database error " + a);
   }
//Writing the sql command to get information from database
string command = "select * from person";

Now, create a SqlDataAdapter object and DataTable object and fill the DataTable from the SqlDataAdapter object. Now assign the DataTable as Datagridview DataSource.

DataTable dt = new DataTable(); //create DataTable object
try
  {
      //Create the SqlDataAdapter object
      SqlDataAdapter adapter = new SqlDataAdapter(command , con);
      //fill the Datatable from data using SqlDataAdapter
      adapter.Fill(dt);
      //sets the datatable as the datasource
      dataGridView1.DataSource=dt;
   }
catch (Exception s)
   {
      MessageBox.Show(s.ToString());
   }

DataGridView to DataTable

Now let's see how to get information from a datagridview to a data table. If the datagridview has a data source, then it is too easy. Only thing you have to do is cast the datagridview data source to a data table.

DataTable dt=(DataTable)dataGridView1.DataSource;

But in some situations, we want user to fill the datagridview with information and later, we want to get the information to a data table. In such situations, datagridview has no data source. Then, we have to write some code to get information from datagridview to a data table.

DataTable datatable = new DataTable();//create DataTable object
datatable.Columns.Add("Id",typeof(int)); //add Columns to DataTable
datatable.Columns.Add("Name", typeof(string));
//read every row in datagridview
foreach (DataGridViewRow r in dataGridView1.Rows)
{
      DataRow drow = datatable.NewRow(); //create a new row
      //add values from datagridview row to datatable row
      drow[0] = r.Cells[0].Value;
      drow[1] = r.Cells[1].Value;
      datatable.Rows.Add(drow); // add row to data table
}

Normally, when we enter data in a datagridview, it will add an additional row below. So we get an additional row with no data with the relevant information. So in the previous example, you will probably get a run time error. To avoid that, you can check for null rows.

try
{
    if (r.Cells[0].Value == null || r.Cells[1].Value == null)
    throw new ArgumentNullException("Values cannot be null");
else
{
    drow[0] = r.Cells[0].Value;
    drow[1] = r.Cells[1].Value;
    dt1.Rows.Add(drow);
}
}
    catch (ArgumentNullException err)
{
    Console.WriteLine(err.Message);
}

Now let's see some important properties of datagridview.

When we add columns to datagridview normally columns won’t fit to entire datagridview space. We can adjust that using:

dataGridView1.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill;

We can change the datagridview selection mode using:

//select full row
dataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect;
//select full column
dataGridView1.SelectionMode = DataGridViewSelectionMode.FullColumnSelect;

Read more @ http://msdn.microsoft.com/en-us/library/wc5cbb9z.