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我目前正在开发一个工作程序，该程序使用组织非常奇怪的 MS Access 数据库中的数据。

我必须从一个表跳到另一个表来获取我需要的信息。

现在我选择的数据少于 200 x 100，但执行所有查询似乎需要很多时间。大约需要 150 秒。

除了我用 php 和 mySql 编写的几个网站之外，我没有真正的数据库背景，所以我想知道你们是否可以快速查看我的代码并告诉我查询的结构和位置是否正确或是否正确是什么让它这么慢。

Dim connectionStr = Constants.Input.MDB.CONNECTION_STRING & _
        "Data Source=" & dbFullPath & ";"

    Dim connection As New System.Data.OleDb.OleDbConnection(connectionStr)

    connection.Open()

    Dim query = "SELECT " & Constants.Input.MDB.Columns.CYCLE_ID & ", " & _
                            Constants.Input.MDB.Columns.COMMAND_ID & ", " & _
                            Constants.Input.MDB.Columns.QUANTITY & ", " & _
                            Constants.Input.MDB.Columns.FINAL_TEMP & ", " & _
                            Constants.Input.MDB.Columns.DATE_TIME & ", " & _
                            Constants.Input.MDB.Columns.DRY_MALAX_TIME & ", " & _
                            Constants.Input.MDB.Columns.TOTAL_MALAX_TIME & _
                " FROM " & Constants.Input.MDB.Tables.CYCLE & _
                " WHERE " & Constants.Input.MDB.Columns.DATE_TIME & _
                " BETWEEN #" & startDate.ToString("yyyy/MM/dd") & "# AND #" & endDate.ToString("yyyy/MM/dd") & "#"

    Dim dbCommand = New System.Data.OleDb.OleDbCommand(query, connection)

    ' Table readers
    Dim reader_cycle = dbCommand.ExecuteReader

    Dim reader_command As System.Data.OleDb.OleDbDataReader

    Dim reader_strCache As System.Data.OleDb.OleDbDataReader

    Dim reader_recipe As System.Data.OleDb.OleDbDataReader

    Dim reader_coldFeedsRecipeDetails As System.Data.OleDb.OleDbDataReader

    Dim reader_materials As System.Data.OleDb.OleDbDataReader

    Dim reader_cycleDetails As System.Data.OleDb.OleDbDataReader

    Dim reader_location As System.Data.OleDb.OleDbDataReader

    ' Cycle table
    While (reader_cycle.Read)

        Dim row(nbCols) As String

        row(Constants.Input.MDB.CYCLE_ID_COLUMN_INDEX) = reader_cycle.Item(0)
        row(Constants.Input.MDB.COMMAND_ID_COLUMN_INDEX) = reader_cycle.Item(1)
        row(Constants.Input.MDB.TOTAL_QTY_COLUMN_INDEX) = reader_cycle.Item(2)
        row(Constants.Input.MDB.FINAL_TEMP_COLUMN_INDEX) = reader_cycle.Item(3)
        Dim date_time = CStr(reader_cycle.Item(4)).Split(" "c)
        row(Constants.Input.MDB.DATE_COLUMN_INDEX) = date_time(0)
        row(Constants.Input.MDB.TIME_COLUMN_INDEX) = date_time(1)
        row(Constants.Input.MDB.TOTAL_MALAX_TIME_COLUMN_INDEX) = reader_cycle.Item(5)
        row(Constants.Input.MDB.DRY_MALAX_TIME_COLUMN_INDEX) = reader_cycle.Item(6)

        query = "SELECT " & Constants.Input.MDB.Columns.FORMULA_NAME_ID & ", " & _
                            Constants.Input.MDB.Columns.TRUCK_ID & _
                " FROM " & Constants.Input.MDB.Tables.COMMAND & _
                " WHERE " & Constants.Input.MDB.Columns.COMMAND_ID & " " & _
                " = " & row(Constants.Input.MDB.COMMAND_ID_COLUMN_INDEX)

        dbCommand = New System.Data.OleDb.OleDbCommand(query, connection)

        reader_command = dbCommand.ExecuteReader

        Dim recipeNameID As String

        ' Command table
        While (reader_command.Read)

            recipeNameID = reader_command.Item(0)
            row(Constants.Input.MDB.TRUCK_ID_COLUMN_INDEX) = reader_command.Item(1)

        End While ' End Command Table

        reader_command.Close()

        query = "SELECT " & Constants.Input.MDB.Columns.STRING_CONTENT & _
                            " FROM " & Constants.Input.MDB.Tables.STRING_CACHE & _
                            " WHERE " & Constants.Input.MDB.Columns.STRING_ID & _
                            " = " & recipeNameID

        dbCommand = New System.Data.OleDb.OleDbCommand(query, connection)

        reader_strCache = dbCommand.ExecuteReader

        ' String Cache (formula name)
        While (reader_strCache.Read)

            row(Constants.Input.MDB.RECIPE_NAME_COLUMN_INDEX) = reader_strCache.Item(0)

        End While ' End String Cache

        reader_strCache.Close()

        query = "SELECT " & Constants.Input.MDB.Columns.RECIPE_DESC & ", " & _
                            Constants.Input.MDB.Columns.QUANTITY & ", " & _
                            Constants.Input.MDB.Columns.COLD_FEEDS_RECIPE_ID & _
                " FROM " & Constants.Input.MDB.Tables.RECIPES & _
                " WHERE " & Constants.Input.MDB.Columns.RECIPE_NAME & _
                " = " & "'" & row(Constants.Input.MDB.RECIPE_NAME_COLUMN_INDEX) & "'"

        dbCommand = New System.Data.OleDb.OleDbCommand(query, connection)

        reader_recipe = dbCommand.ExecuteReader

        Dim coldFeedRecipeID As Object

        ' Recipe
        While (reader_recipe.Read)

            row(Constants.Input.MDB.RECIPE_DESC_COLUMN_INDEX) = reader_recipe.Item(0)
            row(Constants.Input.MDB.RECIPE_QTY_COLUMN_INDEX) = reader_recipe.Item(1)
            coldFeedRecipeID = reader_recipe.Item(2)

        End While ' End Recipe

        reader_recipe.Close()

        If (Not IsDBNull(coldFeedRecipeID)) Then


            query = "SELECT " & Constants.Input.MDB.Columns.MATERIAL_ID & ", " & _
                                Constants.Input.MDB.Columns.MATERIAL_PERCENTAGE & _
                    " FROM " & Constants.Input.MDB.Tables.COLD_FEEDS_RECIPES_DETAILS & _
                    " WHERE " & Constants.Input.MDB.Columns.CFRD_TABLE_RECIPE_ID & _
                    " = " & coldFeedRecipeID

            dbCommand = New System.Data.OleDb.OleDbCommand(query, connection)

            reader_coldFeedsRecipeDetails = dbCommand.ExecuteReader


            ' Cold Feeds Recipe Details
            While (reader_coldFeedsRecipeDetails.Read)

                query = "SELECT " & Constants.Input.MDB.Columns.LOCATION_NAME & _
                    " FROM " & Constants.Input.MDB.Tables.LOCATION & _
                    " WHERE " & Constants.Input.MDB.Columns.MATERIAL_ID & _
                    " = " & reader_coldFeedsRecipeDetails.Item(0)

                dbCommand = New System.Data.OleDb.OleDbCommand(query, connection)

                reader_location = dbCommand.ExecuteReader

                Dim locationName As String

                ' Location
                If (reader_location.Read) Then

                    locationName = reader_location.Item(0)
                Else
                    locationName = Constants.Input.MDB.DEFAULT_LOCATION

                End If ' End Location

                Dim locationIndex = Constants.Input.MDB.getColumnIndex(locationName)

                row(locationIndex + Constants.Input.MDB.LOCATION_ROW_INDEX) = locationName

                reader_location.Close()

                query = "SELECT " & Constants.Input.MDB.Columns.MATERIAL_NAME & _
                        " FROM " & Constants.Input.MDB.Tables.MATERIALS & _
                        " WHERE " & Constants.Input.MDB.Columns.MATERIAL_ID & _
                        " = " & reader_coldFeedsRecipeDetails.Item(0)

                dbCommand = New System.Data.OleDb.OleDbCommand(query, connection)

                reader_materials = dbCommand.ExecuteReader

                ' Materials
                While (reader_materials.Read)

                    row(locationIndex + Constants.Input.MDB.MATERIAL_NAME_ROW_INDEX) = reader_materials.Item(0)
                    row(locationIndex + Constants.Input.MDB.PERCENTAGE_ROW_INDEX) = reader_coldFeedsRecipeDetails.Item(1)

                End While ' End materials

                reader_materials.Close()

            End While ' End Cold Feeds ...

            reader_coldFeedsRecipeDetails.Close()

        End If

        query = "SELECT " & Constants.Input.MDB.Columns.MATERIAL_NAME_ID & ", " & _
                            Constants.Input.MDB.Columns.FORMULA_QUANTITY & ", " & _
                            Constants.Input.MDB.Columns.DOSAGE_QUANTITY & ", " & _
                            Constants.Input.MDB.Columns.REAL_QUANTITY & ", " & _
                            Constants.Input.MDB.Columns.LOCATION & ", " & _
                            Constants.Input.MDB.Columns.MANUEL_MODE & _
                " FROM " & Constants.Input.MDB.Tables.CYCLE_DETAILS & _
                " WHERE " & Constants.Input.MDB.Columns.CYCLE_ID & _
                " = " & row(Constants.Input.MDB.CYCLE_ID_COLUMN_INDEX)

        dbCommand = New System.Data.OleDb.OleDbCommand(query, connection)

        reader_cycleDetails = dbCommand.ExecuteReader

        ' Cycle details
        While (reader_cycleDetails.Read)

            Dim materialNameID = reader_cycleDetails.Item(0)

            Dim location = reader_cycleDetails.Item(4)

            query = "SELECT " & Constants.Input.MDB.Columns.LOCATION_NAME & _
                    " FROM " & Constants.Input.MDB.Tables.LOCATION & _
                    " WHERE " & Constants.Input.MDB.Columns.LOCATION_ID & _
                    " = " & location

            dbCommand = New System.Data.OleDb.OleDbCommand(query, connection)

            reader_location = dbCommand.ExecuteReader

            Dim locationName As String

            ' Location
            While (reader_location.Read)

                locationName = reader_location.Item(0)

            End While ' End Location

            Dim locationIndex = Constants.Input.MDB.getColumnIndex(locationName)

            row(locationIndex + Constants.Input.MDB.LOCATION_ROW_INDEX) = locationName

            reader_location.Close()

            query = "SELECT " & Constants.Input.MDB.Columns.STRING_CONTENT & _
                    " FROM " & Constants.Input.MDB.Tables.STRING_CACHE & _
                    " WHERE " & Constants.Input.MDB.Columns.STRING_ID & _
                    " = " & materialNameID

            dbCommand = New System.Data.OleDb.OleDbCommand(query, connection)

            reader_strCache = dbCommand.ExecuteReader

            ' String Cache (formula name)
            While (reader_strCache.Read)

                row(locationIndex + Constants.Input.MDB.MATERIAL_NAME_ROW_INDEX) = reader_strCache.Item(0)

            End While ' End String Cache

            reader_strCache.Close()

            row(locationIndex + Constants.Input.MDB.RECIPE_QTY_ROW_INDEX) = reader_cycleDetails.Item(1)
            row(locationIndex + Constants.Input.MDB.DOSAGE_QTY_ROW_INDEX) = reader_cycleDetails.Item(2)
            row(locationIndex + Constants.Input.MDB.REAL_QTY_ROW_INDEX) = reader_cycleDetails.Item(3)
            row(locationIndex + Constants.Input.MDB.MANUAL_ROW_INDEX) = reader_cycleDetails.Item(5)

        End While ' End cycle details

        reader_cycleDetails.Close()

        rowList.AddLast(row)

    End While ' End Cycle

    reader_cycle.Close()

    connection.Close()

    Return rowList
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1 回答 1

1

您正在对数据库进行许多不同的选择。每次打开和关闭连接时，除了实际查询的成本外，还有很大的 IO 成本。

正如@RobertHarvey 提到的，您需要学习使用 JOIN。

于 2013-01-23T22:24:32.823 回答