データの生成（create）

  Const GET_MARKET_ID_SQL As String = " (select market_id from t_market where market_name = :market_name) "

  Const GET_CATEGORY_ID_SQL As String = " (select category_id from t_category where category_name = :category_name) "

  Const GET_ITEM_ID_SQL As String = " (select item_id from t_item where category_id = " & GET_CATEGORY_ID_SQL & " and item_name = :item_name) "

  Const SET_VALUE_SQL As String = "insert into t_value (term, company_id, market_id, datetime, category_id, item_id, value) " & _
                                  "values (:term, :company_id, " & GET_MARKET_ID_SQL & ", :datetime, " & GET_CATEGORY_ID_SQL & ", " & GET_ITEM_ID_SQL & ", :value);"

  Protected _createCom As NpgsqlCommand
  Public Property CreateCom As NpgsqlCommand
    Set(ByVal value As NpgsqlCommand)
      _createCom = value
    End Set
    Get
      Return _createCom
    End Get
  End Property

  Protected _tx As NpgsqlTransaction
  Public ReadOnly Property Tx As NpgsqlTransaction
    Get
      Return _tx
    End Get
  End Property

  Sub BeginTx()
    _tx = _conn.BeginTransaction()
    _createCom = New NpgsqlCommand(SET_VALUE_SQL, _conn, _tx)
    InitCreateUpdate(_createCom)
  End Sub

  Sub CommitTx()
    _tx.Commit()
  End Sub

  Private Sub InitCreateUpdate(ByVal command As NpgsqlCommand)
    command.Parameters.Add(New NpgsqlParameter("term", DbType.String))
    command.Parameters.Add(New NpgsqlParameter("company_id", DbType.Int32))
    command.Parameters.Add(New NpgsqlParameter("market_name", DbType.String))
    command.Parameters.Add(New NpgsqlParameter("datetime", DbType.DateTime))
    command.Parameters.Add(New NpgsqlParameter("category_name", DbType.String))
    command.Parameters.Add(New NpgsqlParameter("item_name", DbType.String))
    command.Parameters.Add(New NpgsqlParameter("value", DbType.Double))
    command.Prepare()
  End Sub

  Sub Create(ByVal sv As SeqValue)
    CreateUpdate(_createCom, sv)
  End Sub

  Private Shared Sub CreateUpdate(ByVal command As NpgsqlCommand, ByVal sv As SeqValue)
    command.Parameters("term").Value = sv.term
    command.Parameters("company_id").Value = sv.company_id
    command.Parameters("market_name").Value = sv.market.DBItemName
    command.Parameters("datetime").Value = sv.datetime
    command.Parameters("category_name").Value = sv.category_name
    command.Parameters("item_name").Value = sv.item_name
    command.Parameters("value").Value = sv.value
    command.ExecuteNonQuery()
  End Sub

Dim dao As New SeqValueDAO
dao.BeginTx()
dao.Create(seqValue1)
dao.Create(seqValue2)
dao.Create(seqValue3)
' ・・・
dao.CommitTx()