ADO.Net

Datasets kunnen in een session opgeslagen worden session("mds") =mds

Commands object

• Executereader --> execute and returns a datareader

• Executenonquery --> executes and reutrns nothing bijv. update, insert and delete

• Executescalar --> execute and returns the first value

voorbeeld executereader

private sub datareaderfromsql()

    dim cnn as new sqlconnection(constants.sqlconnectonstring)

    dim strsql as string="select * from employees"

    dim cmd as new sqlcommand(strsql, cnn)

    dim dr as sqldatareader

    try

        cnn.open()

        dr=cmd.executereader()

        do while dr.read

            lstdemo.item.add(string.format ("{0}",dr("firstname"), dr("lastname"), dr("homephone"))

        loop

        catch e as exeption

            lblerror .text = e.tostring

        finnaly

            cmd.dispose

            dr.close

            cnn.close

            cnn.dispose

    end try

end sub           

voorbeeld storedprocedure

private sub callstoredprocedure()

    dim cnn as new sqlconnection(constants.sqlconnectonstring)

    dim cmd as new sqlcommand("custorderhist", cnn)

    dim dr as sqldatareader

    dim strcast as string

    try

        strcast =lstcustomerid.selecteditem.tostring

        cnn.open()

        cmd.commandtype = commandtype.storedprocedure

        dim prm as sqlparameter = cmd.parameters.add("@customerid",strcast)

        dr=cmd.executereader(commandbehavior.closeconnection)

        while dr.read

            lstdemo.item.add(string.format ("{0}",dr("firstname"), dr("lastname"), dr("homephone"))

        end while

        catch e as exeption

            lblerror .text = e.tostring

        finnaly

            cmd.dispose

            dr.close

            cnn.close

            cnn.dispose

    end try

end sub