SqlDataReader HasRows but doesn't Read

Question

I'm using a SqlDataReader to retrieve database information to put into a javascript string. I get SqlDataReader.HasRows=True, and if I call my string building without reading the data reader first, I get the proper string. If I try to loop on the reader though, nothing comes out.

The following code returns a properly formed string, but only for the first record:

Function sFnLoadCodingLines() As String
    Dim cmdCoding As SqlCommand, drCoding As SqlDataReader, con As New SqlConnection(strcon)
    Dim sTemp As String = ""
    Dim lInvoiceID As Long

    If Not IsNumeric(CLng(Page.Request.QueryString("InvoiceID"))) Then
        sFnLoadCodingLines = ""
        Exit Function
    End If


    lInvoiceID = CLng(Page.Request.QueryString("InvoiceID"))

    cmdCoding = New SqlCommand
    cmdCoding.CommandText = "SELECT BU,DEPT,AccNo,Qty,Amount,Description,EMP,VARIETAL,BRAND,STATE,PROJECT " & _
                                "FROM OI_tblCoding WHERE isDeleted=0 AND InvoiceID=" & lInvoiceID
    cmdCoding.Connection = con
    con.Open()
    drCoding = cmdCoding.ExecuteReader
    drCoding.Read()

    If drCoding.HasRows() Then

        sTemp = sTemp & "addRowToTable(""" & drCoding("BU").ToString & _
            """,""" & drCoding("DEPT").ToString & _
            """,""" & drCoding("AccNo").ToString & _
            """,""" & drCoding("Qty").ToString & _
            """,""" & drCoding("Amount").ToString & _
            """,""" & drCoding("Description").ToString & _
            """,""" & drCoding("EMP").ToString & _
            """,""" & drCoding("VARIETAL").ToString & _
            """,""" & drCoding("BRAND").ToString & _
            """,""" & drCoding("STATE").ToString & _
            """,""" & drCoding("PROJECT").ToString & """);" & vbCrLf

        sFnLoadCodingLines = sTemp

    Else
        sFnLoadCodingLines = ""
    End If

    con.Close()

End Function

The following record returns an empty string:

Function sFnLoadCodingLines() As String
    Dim cmdCoding As SqlCommand, drCoding As SqlDataReader, con As New SqlConnection(strcon)
    Dim sTemp As String = ""
    Dim lInvoiceID As Long

    If Not IsNumeric(CLng(Page.Request.QueryString("InvoiceID"))) Then
        sFnLoadCodingLines = ""
        Exit Function
    End If


    lInvoiceID = CLng(Page.Request.QueryString("InvoiceID"))

    cmdCoding = New SqlCommand
    cmdCoding.CommandText = "SELECT BU,DEPT,AccNo,Qty,Amount,Description,EMP,VARIETAL,BRAND,STATE,PROJECT " & _
                                "FROM OI_tblCoding WHERE isDeleted=0 AND InvoiceID=" & lInvoiceID
    cmdCoding.Connection = con
    con.Open()
    drCoding = cmdCoding.ExecuteReader
    drCoding.Read()

    If drCoding.HasRows() Then

        While drCoding.Read()
            'addRowToTable(sBU, sDPT, sAcct, dbQty, dbAmt, sDesc, sEmp, sVar, sBrand, sState, sProj)
            sTemp = sTemp & "addRowToTable(""" & drCoding("BU").ToString & _
                            """,""" & drCoding("DEPT").ToString & _
                            """,""" & drCoding("AccNo").ToString & _
                            """,""" & drCoding("Qty").ToString & _
                            """,""" & drCoding("Amount").ToString & _
                            """,""" & drCoding("Description").ToString & _
                            """,""" & drCoding("EMP").ToString & _
                            """,""" & drCoding("VARIETAL").ToString & _
                            """,""" & drCoding("BRAND").ToString & _
                            """,""" & drCoding("STATE").ToString & _
                            """,""" & drCoding("PROJECT").ToString & """);" & vbCrLf

        End While

        sFnLoadCodingLines = sTemp

    Else
        sFnLoadCodingLines = ""
    End If

    con.Close()

End Function

Answer 1

But you ARE reading the data in both cases. You call ExecuteReader and then you call Read immediately after that, before testing HasRows. Get rid of that first Read call and your loop will work as you expect. The first code would then fail as it should because you will not be calling Read at all.