SqlDataReader.Read Method ()

 

Advances the SqlDataReader to the next record.

Namespace:   System.Data.SqlClient
Assembly:  System.Data (in System.Data.dll)

Public Overrides Function Read As Boolean

Return Value

Type: System.Boolean

true if there are more rows; otherwise false.

Exception Condition
SqlException

SQL Server returned an error while executing the command text.

The default position of the SqlDataReader is before the first record. Therefore, you must call Read to begin accessing any data.

Only one SqlDataReader per associated SqlConnection may be open at a time, and any attempt to open another will fail until the first one is closed. Similarly, while the SqlDataReader is being used, the associated SqlConnection is busy serving it until you call Close.

The following example creates a SqlConnection, a SqlCommand, and a SqlDataReader. The example reads through the data, writing it out to the console window. The code then closes the SqlDataReader. The SqlConnection is closed automatically at the end of the using code block.

Option Explicit On
Option Strict On

Imports System.Data
Imports System.Data.SqlClient

Module Module1

    Sub Main()
        Dim str As String = "Data Source=(local);Initial Catalog=Northwind;" _
       & "Integrated Security=SSPI;"
        ReadOrderData(str)
    End Sub

    Private Sub ReadOrderData(ByVal connectionString As String)
        Dim queryString As String = _
            "SELECT OrderID, CustomerID FROM dbo.Orders;"

        Using connection As New SqlConnection(connectionString)
            Dim command As New SqlCommand(queryString, connection)
            connection.Open()

            Dim reader As SqlDataReader = command.ExecuteReader()

            ' Call Read before accessing data.
            While reader.Read()
                ReadSingleRow(CType(reader, IDataRecord))
            End While

            ' Call Close when done reading.
            reader.Close()
        End Using
    End Sub

    Private Sub ReadSingleRow(ByVal record As IDataRecord)
       Console.WriteLine(String.Format("{0}, {1}", record(0), record(1)))

    End Sub

End Module

.NET Framework
Available since 1.1
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