DataAdapter

MSDN > .NET > Framework > Data Access > ADO.NET > DataAdapter

The DataAdapter is a core component of ADO.NET that acts as a bridge between a DataSet and a data source. It provides the functionality to retrieve data from a data source and populate a DataSet, and to reconcile changes made to the data in the DataSet back to the data source.

A DataAdapter exposes four primary methods that enable these operations:

• Fill(): Retrieves data from the data source and populates a DataSet.
• FillSchema(): Retrieves database schema information and creates a DataTable in the DataSet without populating it with data.
• Update(): Reconciles changes made to the data in the DataSet back to the data source.
• SelectCommand: A property that retrieves the SQL statement or stored procedure used to select records from the data source.

ADO.NET provides specific implementations of DataAdapter for different data providers, such as:

• SqlDataAdapter for SQL Server.
• OracleDataAdapter for Oracle databases.
• OleDbDataAdapter for OLE DB data sources.
• OdbcDataAdapter for ODBC data sources.

Key Concepts

Loading Data (Fill)

The Fill() method is used to load data from a data source into a DataSet. It executes the SelectCommand and uses a DataTable (or creates one if it doesn't exist) to store the retrieved rows.

using System.Data;
using System.Data.SqlClient; // Or your specific provider

// Assume connectionString and selectCommandText are defined
using (SqlConnection connection = new SqlConnection(connectionString))
{
    SqlDataAdapter adapter = new SqlDataAdapter(selectCommandText, connection);
    DataSet dataSet = new DataSet();
    adapter.Fill(dataSet, "Customers"); // Fills the DataSet with data into a DataTable named "Customers"
}
            

Updating Data (Update)

The Update() method is used to send changes made in a DataSet back to the data source. This involves inserting, updating, or deleting rows in the data source based on the RowState property of the rows in the DataSet.

To support the Update() operation, the DataAdapter must have its InsertCommand, UpdateCommand, and DeleteCommand properties configured appropriately. If these are not set, attempting to update will result in an exception.

// Assume adapter, dataSet, and connection are already set up and filled

// Modify data in dataSet.Tables["Customers"]...
// dataSet.Tables["Customers"].Rows[0]["ContactName"] = "New Name";
// dataSet.Tables["Customers"].Rows[0].Delete();

// Update the data source
// adapter.InsertCommand = ...;
// adapter.UpdateCommand = ...;
// adapter.DeleteCommand = ...;
int rowsAffected = adapter.Update(dataSet, "Customers");
            

DataAdapter Events

DataAdapter provides several events that allow you to hook into the data retrieval and update process:

• RowUpdating: Occurs before a row is updated in the data source.
• RowUpdated: Occurs after a row has been updated in the data source.
• Fillizando: Occurs before the Fill() operation begins.
• FillLoaded: Occurs after the Fill() operation has completed.

See Also

• DataSet
• Connecting to Data Sources
• Commands and Parameters