ADO.NET ExecuteReader in OleDbCommand Object

The ExecuteReader() method in the OleDbCommand Object sends the SQL statements to the Connection Object and populates an OleDbDataReader Object based on the SQL statement provided. When the ExecuteReader() method is executed, it instantiates an OleDbDataReader Object from the System.Data.OleDb namespace.


The OleDbDataReader Object is a stream-based, forward-only, read-only mechanism for retrieving query results from the data source. It provides a way to efficiently read and navigate through the result set returned by the SQL statement. Similar to SqlDataReader, the OleDbDataReader Object is designed for retrieving data and does not support updating or modifying the data in the data source.

It is important to note that you cannot directly create an instance of the OleDbDataReader Object in your code. Instead, it is created by calling the ExecuteReader() method of a Command Object, such as the OleDbCommand Object. The ExecuteReader() method initiates the execution of the SQL statement, and once executed, it returns an OleDbDataReader Object that you can use to read the retrieved data row by row.

Full Source VB.NET
Imports System.Data.OleDb Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim connetionString As String Dim cnn As OleDbConnection Dim cmd As OleDbCommand Dim sql As String Dim reader As OleDbDataReader connetionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Your mdb filename;" sql = "Your SQL Statement Here like Select * from product" cnn = New OleDbConnection(connetionString) Try cnn.Open() cmd = New OleDbCommand(sql, cnn) reader = cmd.ExecuteReader() While reader.Read() MsgBox(reader.Item(0) & " - " & reader.Item(1) & " - " & reader.Item(2)) End While reader.Close() cmd.Dispose() cnn.Close() Catch ex As Exception MsgBox("Can not open connection ! ") End Try End Sub End Class


The ExecuteReader() method in the OleDbCommand Object is responsible for executing SQL statements and creating an OleDbDataReader Object. This OleDbDataReader Object allows you to read and retrieve the result set from the data source in a forward-only manner, enabling efficient data retrieval and processing.