Public Class BidDAO
    ' 入札処理
    Public Shared Function ExecBid(itemid As Integer, userid As Integer, price As Integer) As BidErrorEnum

        Using con As New OracleConnection(ConfigurationManager.ConnectionStrings("OracleDB").ConnectionString)
            ' ロック、最高値取得用Command
            Dim cmd4lock As New OracleCommand(
                "SELECT * FROM 異常系1_応札データ WHERE 商品id=:ID for update", con)
            cmd4lock.Parameters.Add(New OracleParameter("ID", OracleDbType.Int64))
            ' 最高値取得
            Dim cmd4max As New OracleCommand(
                "SELECT MAX(応札金額) as 応札最高値 FROM 異常系1_応札データ WHERE 商品id=:ID", con)
            cmd4max.Parameters.Add(New OracleParameter("ID", OracleDbType.Int64))
            ' 入札データ書き込み用Command
            Dim cmd4insert As New OracleCommand("INSERT INTO 異常系1_応札データ(商品ID, ユーザーID, 応札金額) VALUES(:itemid, :userid, :price)", con)
            cmd4insert.Parameters.Add(New OracleParameter("itemid", OracleDbType.Int64))
            cmd4insert.Parameters.Add(New OracleParameter("userid", OracleDbType.Int64))
            cmd4insert.Parameters.Add(New OracleParameter("price", OracleDbType.Int64))

            con.Open()

            ' トランザクションオブジェクト取得
            Using tx As OracleTransaction = con.BeginTransaction
                cmd4lock.Transaction = tx
                cmd4insert.Transaction = tx

                Try
                    ' ロック
                    cmd4lock.Parameters("id").Value = itemid
                    cmd4lock.ExecuteScalar()

                    ' 最高値取得
                    Dim maxPrice As Integer = 0

                    Try
                        cmd4max.Parameters("id").Value = itemid
                        maxPrice = cmd4max.ExecuteScalar
                    Catch ex As InvalidCastException
                        maxPrice = 0
                    End Try

                    If maxPrice >= price Then
                        ' 入札金額が最高値以下
                        tx.Rollback()

                        Return BidErrorEnum.UnderPriceError
                    End If

                    ' 入札データ書き込み
                    cmd4insert.Parameters("itemid").Value = itemid
                        cmd4insert.Parameters("userid").Value = userid
                        cmd4insert.Parameters("price").Value = price
                        cmd4insert.ExecuteNonQuery()

                        tx.Commit()
                    Catch ex As OracleException
                        ' DBアクセス時にエラー
                        tx.Rollback()
                    ' なにもできないので、再スロー
                    Throw ex
                    'Catch ex As Exception
                    '    ' 入札金額が応札最高値以下
                    '    tx.Rollback()

                    '    Return BidErrorEnum.UnderPriceError
                End Try
            End Using

        End Using

        Return BidErrorEnum.Success
    End Function
End Class