Winform practice sqlcommandbuilder

Public partial class form1: Form
{< br> // declare a public dt
datatable dt = NULL;
string strconn = string. empty;
// declare a public SQL text variable, which is used for query and update.
string sqltext = string. empty;

Public form1 ()
{
Initializecomponent ();
// Initialize the variable
Datagridview1.selectionmode = datagridviewselectionmode. fullrowselect;
Strconn = "Server =.; uid = huashanlin; Pwd = 123; database = testdb ";
Sqltext = "select * From t_order ";
// Load data
Getdate ();
}

Private void getdate ()
{
Using (sqlconnection conn = new sqlconnection (strconn ))
{
Sqldataadapter SDA = new sqldataadapter ("select * From t_user", Conn );
// The data table named DT must be public.
Dt = new datatable ();
SDA. Fill (DT );
// Bind the datagridview
Datagridview1.datasource = DT;
// Bind the text box
Tb1.databindings. Clear ();
Tb1.databindings. Add ("text", DT, "userid ");
Tb2.databindings. Clear ();
Tb2.databindings. Add ("text", DT, "username ");
}
}

Private void btnalter_click (Object sender, eventargs E)
{
Using (sqlconnection conn = new sqlconnection (strconn ))
{
Sqldataadapter SDA = new sqldataadapter ("select * From t_user", Conn );
Sqlcommandbuilder SCB = new sqlcommandbuilder (SDA );
SDA. Update (DT );
MessageBox. Show ("updated successfully ");
Getdate ();
}
}

}