データの削除（delete）

  Const DELETE_VALUE_SQL As String = "delete from t_value " & _
                  "where term = :term and company_id = :company_id and market_id = " & GET_MARKET_ID_SQL & " and datetime = :datetime " & _
                  " and category_id = " & GET_CATEGORY_ID_SQL & " and item_id = " & GET_ITEM_ID_SQL & " ;"

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

    _deleteCom = New NpgsqlCommand(DELETE_VALUE_SQL, _conn, _tx)
    _deleteCom.Parameters.Add(New NpgsqlParameter("term", DbType.String))
    _deleteCom.Parameters.Add(New NpgsqlParameter("company_id", DbType.Int32))
    _deleteCom.Parameters.Add(New NpgsqlParameter("market_name", DbType.String))
    _deleteCom.Parameters.Add(New NpgsqlParameter("datetime", DbType.DateTime))
    _deleteCom.Parameters.Add(New NpgsqlParameter("category_name", DbType.String))
    _deleteCom.Parameters.Add(New NpgsqlParameter("item_name", DbType.String))
    _deleteCom.Prepare()
  End Sub

  Sub Delete(ByVal sv As SeqValue)
    _deleteCom.Parameters("term").Value = sv.term
    _deleteCom.Parameters("company_id").Value = sv.company_id
    _deleteCom.Parameters("market_name").Value = sv.market.DBItemName
    _deleteCom.Parameters("datetime").Value = sv.datetime
    _deleteCom.Parameters("category_name").Value = sv.category_name
    _deleteCom.Parameters("item_name").Value = sv.item_name
    _deleteCom.ExecuteNonQuery()
  End Sub

Dim dao As New SeqValueDAO
dao.BeginTx()
dao.Create(seqValue1)
dao.Create(seqValue2)
dao.Create(seqValue3)
dao.Update(seqValue4)
dao.Update(seqValue5)
dao.Update(seqValue6)
dao.Delete(seqValue7)
dao.Delete(seqValue8)
dao.Delete(seqValue9)
' ・・・
dao.CommitTx()