While working with disconnected approach we works with storing and retrieving data from buffers to select operation.
Here Adapter acts like a buffer where the data is contained. But for reading that data we need to store it either in DataTable or in DataSet.
For this purpose we use SqlDataAdapter class that uses the disconnected mode for fetching data from the database.

DataAdapter can be used with two ways :
- OleDbDataAdapter
- SqlDataAdapter
For interacting with MsAccess or other data we can use this OleDb type adapter.
using OleDbDataAdapter;
private void OleDbDataAdapter_Click(object sender, System.Event Args e)
{
//Create a connection object
string ConnectionString = @"provider=Microsoft.Jet.OLEDB.4.0;" +
"Data Source= C:/northwind.mdb";
string SQL = "SELECT * FROM Orders";
OleDbConnection conn = new OleDbConnection(ConnectionString);
// open the connection
conn.Open( );
// Create an OleDbDataAdapter object
OleDbDataAdapter adapter = new OleDbDataAdapter();
adapter.SelectCommand = new OleDbCommand(SQL, conn);
// Create Data Set object
DataSet ds = new DataSet("orders");
// Call DataAdapter's Fill method to fill data from the
// DataAdapter to the DataSet
adapter.Fill(ds);
// Bind dataset to a DataGrid control
dataGrid1.DataSource = ds.DefaultViewManager;
}
And to interact with SqlServer database we will use SqlDataAdapter for it.
using SqlDataAdapter;
private void SqlDataAdapter_Click(object sender, System.EventArgs e)
{
string ConnectionString = "Integrated Security = SSPI;" +
"Initial catalog = Northwind;" + " Data Source =MAIN-SERVER; ";
string SQL = "SELECT CustomerID, CompanyName FROM Customers";
SqlConnection conn = new SqlConnection(ConnectionString);
// open the connection
conn.Open( );
//Create a SqlDataAdapter object
SqlDataAdapter adapter = new SqlDataAdapter(SQL, conn);
// Call DataAdapter's Fill method to fill data from the
// Data Adapter to the DataSet
DataSet ds = new DataSet("Customers");
adapter.Fill(ds);
// Bind data set to a DataGrid control
dataGrid1.DataSource = ds.DefaultViewManager;
}
For this we will use disconnected approach where there is no need of opening and closing the connection.
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