How to: Iterate through Records in a DataReader (Visual Basic) 

This example iterates through a data reader created using a data adapter's select command as well as maintaining a count of records read.

Dim reader As SqlClient.SqlDataReader
Dim recordData As String = ""
Dim recordCount As Integer = 0
Dim i As Integer = 0

sqlConnection1.Open()

reader = sqlDataAdapter1.SelectCommand.ExecuteReader()

While reader.Read()

    For i = 0 To reader.FieldCount - 1
        recordData &= reader(i).ToString()
        recordData &= "-"
    Next

    recordData &= ControlChars.CrLf
    recordCount += 1
End While

sqlConnection1.Close()
MessageBox.Show("Records processed: " & recordCount)
MessageBox.Show("Data:" & ControlChars.CrLf & recordData)

This code example is also available as an IntelliSense code snippet. In the code snippet picker, it is located in Data - Designer features and ADO.NET. For more information, see How to: Insert Snippets Into Your Code (Visual Basic).

This example requires:

• A project reference to System.data.dll.

• Access to the members of the System.Data namespace. Add an Imports statement if you are not fully qualifying member names in your code. For more information, see Imports Statement.

• A data connection named sqlConnection1.

• A SQLDataAdapter object named sqlDataAdapter1.

The following conditions may cause an exception:

• The database is unavailable (OleDbException Class, SqlException Class, OdbcException Class, or OracleException Class, exception will be specific to your database).

OleDbDataReader Class
SqlDataReader Class
OdbcDataReader Class
OracleDataReader Class

Preparing Your Application to Receive Data
Editing Data in Your Application