Click here to Skip to main content
Click here to Skip to main content
Articles » Database » Database » Databases » Downloads
 
Add your own
alternative version

Object-Oriented database design with the DatabaseObjects library

, 31 Jan 2007
Demonstrates creating object-oriented database systems with the DatabaseObjects library.
databaseobjects_demo_net.zip
VB.NET
demo
source
Northwind
NorthwindDB
bin
Northwind.vbproj.user
AxInterop.SHDocVw.dll
DatabaseObjects.dll
Interop.SHDocVw.dll
Northwind.exe
NorthwindDatabase.dll
NorthwindDatabase.vbproj.user
Attributes
bin
Database
DatabaseObjects.vbproj.user
Misc
SQL
DatabaseObjects.dll
Data
mysql_northwind.zip
Documentation
DatabaseObjects.chm
databaseobjects_demo_vb6.zip
VB6
demo
regsvr32.exe
source
Northwind
Northwind.vbg
NorthwindDB
ControlAnchor.cls
frmMain.frm
frmMain.frx
frmOrder.frm
frmOrder.frx
frmProducts.frm
frmProducts.frx
frmProductSearch.frm
frmProductSearch.frx
frmProductSearchExtended.frm
frmProductSearchExtended.frx
frmSuppliers.frm
frmSuppliers.frx
Northwind.exe
northwind.RES
Northwind.vbp
Categories.cls
Category.cls
Data.bas
LateBoundObject.cls
NorthwindDatabase.cls
NorthwindDatabase.OBJ
NorthwindDB.dll
NorthwindDB.vbp
Order.cls
OrderDetail.cls
OrderDetails.cls
Orders.cls
Product.cls
Products.cls
ProductSearch.cls
Supplier.cls
Suppliers.cls
bin
Database.cls
DBO.vbp
GlobalDatabase.cls
GlobalDatabaseObjects.cls
IDatabaseObject.cls
IDatabaseObjects.cls
IGlobalDatabaseObjects.cls
ISQLStatement.cls
modMisc.bas
SQLAlterTable.cls
SQLAutoIncrementValue.cls
SQLCondition.cls
SQLConditionFieldCompare.cls
SQLConditionInSelect.cls
SQLConditions.cls
SQLConditionSelect.cls
SQLCreateIndex.cls
SQLCreateTable.cls
SQLDelete.cls
SQLDropIndex.cls
SQLDropTable.cls
SQLFieldValue.cls
SQLFieldValues.cls
SQLIndexExists.cls
SQLIndexField.cls
SQLIndexFields.cls
SQLInsert.cls
SQLSelect.cls
SQLSelectField.cls
SQLSelectFields.cls
SQLSelectGroupByField.cls
SQLSelectGroupByFields.cls
SQLSelectOrderByField.cls
SQLSelectOrderByFields.cls
SQLSelectTable.cls
SQLSelectTableJoin.cls
SQLSelectTableJoinCondition.cls
SQLSelectTableJoinConditions.cls
SQLSelectTableJoins.cls
SQLSelectTables.cls
SQLTableExists.cls
SQLTableField.cls
SQLTableFields.cls
SQLUpdate.cls
SQLUpdateCopyField.cls
SQLUpdateCopyFields.cls
DatabaseObjects_vb6.dll
mysql_northwind.zip
images
templates
databaseobjects_classdiagram.jpg
logo.jpg
databaseobjects_src_net.zip
DatabaseObjects.vbproj.user
DatabaseObjects.dll
databaseobjects_src_vb6.zip
Database.cls
DBO.vbp
GlobalDatabase.cls
GlobalDatabaseObjects.cls
IDatabaseObject.cls
IDatabaseObjects.cls
IGlobalDatabaseObjects.cls
ISQLStatement.cls
modMisc.bas
SQLAlterTable.cls
SQLAutoIncrementValue.cls
SQLCondition.cls
SQLConditionFieldCompare.cls
SQLConditionInSelect.cls
SQLConditions.cls
SQLConditionSelect.cls
SQLCreateIndex.cls
SQLCreateTable.cls
SQLDelete.cls
SQLDropIndex.cls
SQLDropTable.cls
SQLFieldValue.cls
SQLFieldValues.cls
SQLIndexExists.cls
SQLIndexField.cls
SQLIndexFields.cls
SQLInsert.cls
SQLSelect.cls
SQLSelectField.cls
SQLSelectFields.cls
SQLSelectGroupByField.cls
SQLSelectGroupByFields.cls
SQLSelectOrderByField.cls
SQLSelectOrderByFields.cls
SQLSelectTable.cls
SQLSelectTableJoin.cls
SQLSelectTableJoinCondition.cls
SQLSelectTableJoinConditions.cls
SQLSelectTableJoins.cls
SQLSelectTables.cls
SQLTableExists.cls
SQLTableField.cls
SQLTableFields.cls
SQLUpdate.cls
SQLUpdateCopyField.cls
SQLUpdateCopyFields.cls
DatabaseObjects_vb6.dll
Option Strict Off
Option Explicit On

Imports DatabaseObjects
Imports System.Collections

Public Class Orders
    Implements IDatabaseObjects
    Implements IEnumerable

    Default Public ReadOnly Property Item(ByVal intIndex As Integer) As Order
        Get

            Return NorthwindDB.Database.ObjectByOrdinal(Me, intIndex)

        End Get
    End Property

    Public ReadOnly Property Count() As Integer
        Get

            Return NorthwindDB.Database.ObjectsCount(Me)

        End Get
    End Property

    Public Sub Delete(ByRef objOrder As Order)

        'The objOrder is passed ByRef because the ObjectDelete function
        'sets the objOrder = Nothing thereby ensuring it can no longer be accidentally used.

        NorthwindDB.Database.ObjectsDeleteAll(objOrder.Details)
        NorthwindDB.Database.ObjectDelete(Me, objOrder)

    End Sub

    Private Function DistinctFieldAutoIncrements() As Boolean Implements IDatabaseObjects.DistinctFieldAutoIncrements

        Return True

    End Function

    Private Function DistinctFieldName() As String Implements IDatabaseObjects.DistinctFieldName

        Return "OrderID"

    End Function

    Private Function ItemInstance() As IDatabaseObject Implements IDatabaseObjects.ItemInstance

        Return New Order

    End Function

    Private Function KeyFieldName() As String Implements IDatabaseObjects.KeyFieldName

    End Function

    Private Function OrderBy() As SQL.SQLSelectOrderByFields Implements IDatabaseObjects.OrderBy

    End Function

    Private Function Subset() As SQL.SQLConditions Implements IDatabaseObjects.Subset

    End Function

    Private Function TableName() As String Implements IDatabaseObjects.TableName

        Return "Orders"

    End Function

    Private Function GetEnumerator() As System.Collections.IEnumerator Implements System.Collections.IEnumerable.GetEnumerator

        Return NorthwindDB.Database.ObjectsList(Me).GetEnumerator

    End Function

    Private Function TableJoins(ByVal objPrimaryTable As SQL.SQLSelectTable, ByVal objTables As SQL.SQLSelectTables) As SQL.SQLSelectTableJoins Implements IDatabaseObjects.TableJoins

    End Function

End Class


Public Class Order
    Implements IDatabaseObject

    Private pintID As Integer
    Private pobjDetails As OrderDetails

    Public ShipName As String
    Public ShipAddress As String
    Public ShipCity As String
    Public ShipRegion As String
    Public ShipPostalCode As String
    Public ShipCountry As String

    Public TheDate As Date
    Public RequiredDate As Date

    Friend ReadOnly Property ID() As Integer
        Get

            'Friend will allow public access within the NorthwindDatabase assembly but will be
            'private outside of the NorthwindDatabase assembly
            Return pintID

        End Get
    End Property

    Public ReadOnly Property Number() As Integer
        Get

            Return pintID

        End Get
    End Property

    Public ReadOnly Property Cost() As Decimal
        Get

            Dim curCost As Decimal
            Dim objDetail As OrderDetail

            For Each objDetail In Me.Details
                curCost = curCost + objDetail.Cost
            Next

            Cost = curCost

        End Get
    End Property

    Public ReadOnly Property Details() As OrderDetails
        Get

            If pobjDetails Is Nothing Then
                pobjDetails = New OrderDetails(Me)
            End If

            Details = pobjDetails

        End Get
    End Property

    Private Property DistinctValue() As Object Implements IDatabaseObject.DistinctValue
        Get

            Return pintID

        End Get

        Set(ByVal Value As Object)

            pintID = Value

        End Set
    End Property

    Private Property IsSaved() As Boolean Implements IDatabaseObject.IsSaved
        Get
            'This function can be implemented using a boolean variable to hold
            'whether this object has been saved or not. However, if the object is
            'using an Identity field the following shortcut can be used as it is
            'logically equivalent. The Property Let IsSaved does
            'not need to be implemented

            Return pintID <> 0

        End Get

        Set(ByVal Value As Boolean)

        End Set
    End Property

    Public Sub Save()

        Try

            NorthwindDB.Database.Transactions.Begin()

            'Save the main header object before saving the details, because if this is a new
            'Order object then the OrderID won't have been set yet and the OrderDetail objects
            'won't save with the correctly associated OrderID.

            NorthwindDB.Database.ObjectSave(NorthwindDB.Orders, Me)

            If Not pobjDetails Is Nothing Then
                'save all of the detail lines
                pobjDetails.Save()
            End If

            NorthwindDB.Database.Transactions.Commit()

        Catch ex As Exception

            NorthwindDB.Database.Transactions.Rollback()
            Throw ex

        End Try

    End Sub

    Private Sub LoadFields(ByVal objFields As SQL.SQLFieldValues) Implements IDatabaseObject.LoadFields

        Me.TheDate = objFields("OrderDate").Value
        Me.RequiredDate = objFields("RequiredDate").Value

        Me.ShipName = objFields("ShipName").Value
        Me.ShipAddress = objFields("ShipAddress").Value
        Me.ShipCity = objFields("ShipCity").Value
        Me.ShipRegion = IIf(objFields("ShipRegion").Value Is DBNull.Value, "", objFields("ShipRegion").Value)
        Me.ShipPostalCode = IIf(objFields("ShipPostalCode").Value Is DBNull.Value, "", objFields("ShipPostalCode").Value)
        Me.ShipCountry = objFields("ShipCountry").Value

    End Sub

    Private Function SaveFields() As SQL.SQLFieldValues Implements IDatabaseObject.SaveFields

        Dim objFields As SQL.SQLFieldValues
        objFields = New SQL.SQLFieldValues

        objFields.Add("OrderDate", Me.TheDate)
        objFields.Add("RequiredDate", Me.RequiredDate)

        objFields.Add("ShipName", Me.ShipName)
        objFields.Add("ShipAddress", Me.ShipAddress)
        objFields.Add("ShipCity", Me.ShipCity)
        objFields.Add("ShipRegion", IIf(Me.ShipRegion = Nothing, DBNull.Value, Me.ShipRegion))
        objFields.Add("ShipPostalCode", IIf(Me.ShipPostalCode = Nothing, DBNull.Value, Me.ShipPostalCode))
        objFields.Add("ShipCountry", Me.ShipCountry)

        Return objFields

    End Function

End Class


Public Class OrderDetails
    Implements IDatabaseObjects
    Implements IEnumerable

    Private pobjParent As Order

    'store each detail in a temporary collection
    Private pobjDetails As ArrayList

    Friend Sub New(ByVal objParent As Order)

        pobjParent = objParent
        LoadDetails()

    End Sub

    Friend ReadOnly Property Parent() As Order
        Get

            Parent = pobjParent

        End Get
    End Property

    Default Public ReadOnly Property Item(ByVal intIndex As Integer) As OrderDetail
        Get

            Return pobjDetails(intIndex)

        End Get
    End Property

    Public ReadOnly Property Count() As Integer
        Get

            Return pobjDetails.Count

        End Get
    End Property

    Friend Sub Save()

        Dim objDetail As OrderDetail

        'Delete all of the Detail lines associated with this Order
        NorthwindDB.Database.ObjectsDeleteAll(Me)

        'Save all of the detail lines. Note that in the IsSaved function
        'in the OrderDetail object is set to false. This ensures that records are always
        'inserted into the database not updated because all of the existing detail records
        'have just been deleted.
        For Each objDetail In Me
            NorthwindDB.Database.ObjectSave(Me, objDetail)
        Next

    End Sub

    Private Sub LoadDetails()

        'Loading all of the OrderDetail objects into a collection is necessary so that
        'any adding, editing or deleting of the detail lines does not affect the database
        'until the Order.Save sub is called.

        pobjDetails = NorthwindDB.Database.ObjectsList(Me)

    End Sub

    Private Function DistinctFieldAutoIncrements() As Boolean Implements IDatabaseObjects.DistinctFieldAutoIncrements

    End Function

    Private Function DistinctFieldName() As String Implements IDatabaseObjects.DistinctFieldName
        'The ProductID uniquely identifies each OrderDetail object within the
        'Order - see the Subset function below. The 'ProductID' field
        'together with the 'OrderID' field will determine which record each OrderDetail
        'object is associated with.

        Return "ProductID"

    End Function

    Private Function ItemInstance() As IDatabaseObject Implements IDatabaseObjects.ItemInstance

        Return New OrderDetail(Me)

    End Function

    Private Function KeyFieldName() As String Implements IDatabaseObjects.KeyFieldName

    End Function

    Private Function OrderBy() As SQL.SQLSelectOrderByFields Implements IDatabaseObjects.OrderBy

    End Function

    Private Function Subset() As SQL.SQLConditions Implements IDatabaseObjects.Subset

        Dim objConditions As SQL.SQLConditions = New SQL.SQLConditions

        objConditions.Add("OrderID", SQL.ComparisonOperator.EqualTo, pobjParent.ID)

        Return objConditions

    End Function

    Private Function TableName() As String Implements IDatabaseObjects.TableName

        Return "Order Details"

    End Function

    Private Function GetEnumerator() As System.Collections.IEnumerator Implements System.Collections.IEnumerable.GetEnumerator

        Return pobjDetails.GetEnumerator

    End Function

    Private Function TableJoins(ByVal objPrimaryTable As DatabaseObjects.SQL.SQLSelectTable, ByVal objTables As DatabaseObjects.SQL.SQLSelectTables) As DatabaseObjects.SQL.SQLSelectTableJoins Implements DatabaseObjects.IDatabaseObjects.TableJoins

    End Function

End Class


Public Class OrderDetail
    Implements IDatabaseObject

    Private pobjParent As OrderDetails
    Private pobjProduct As Product
    Private pcurUnitPrice As Decimal
    Private pintQuantity As Integer
    Private psngDiscount As Single

    Friend Sub New(ByVal objParent As OrderDetails)

        pobjParent = objParent

    End Sub

    Public Property UnitPrice() As Decimal
        Get

            UnitPrice = pcurUnitPrice

        End Get

        Set(ByVal Value As Decimal)

            'check that valid prices are set
            If Value >= 0 Then
                pcurUnitPrice = Value
            Else
                Throw New ArgumentException(Value.ToString)
            End If

        End Set
    End Property

    Public Property Quantity() As Integer
        Get

            Quantity = pintQuantity

        End Get

        Set(ByVal Value As Integer)

            'check that valid quantities are set
            If Value >= 0 Then
                pintQuantity = Value
            Else
                Throw New ArgumentException(Value.ToString)
            End If

        End Set
    End Property

    Public Property Discount() As Single
        Get

            Discount = psngDiscount

        End Get

        Set(ByVal Value As Single)

            If Value >= 0 Then
                psngDiscount = Value
            Else
                Throw New ArgumentException(Value.ToString)
            End If

        End Set
    End Property

    Public Property Product() As Product
        Get

            Product = pobjProduct

        End Get

        Set(ByVal Value As Product)

            If Value Is Nothing Then
                Throw New ArgumentNullException
            End If

            pobjProduct = Value

        End Set
    End Property

    Public ReadOnly Property Cost() As Decimal
        Get

            Return Me.UnitPrice * Me.Quantity

        End Get
    End Property

    Private Property DistinctValue() As Object Implements IDatabaseObject.DistinctValue
        Get

            Return pobjProduct.ID

        End Get

        Set(ByVal Value As Object)

            'This function is called when the object is loaded
            'but can be ignored and done in the LoadFields

        End Set
    End Property

    Private Property IsSaved() As Boolean Implements IDatabaseObject.IsSaved
        Get

            'This is always false because a new record is always written to the database for this
            'object. This is because all of the OrderDetail objects are deleted before saving to the
            'database. See the Order.Save function.
            '

            Return False

        End Get

        Set(ByVal Value As Boolean)

        End Set
    End Property

    Private Sub LoadFields(ByVal objFields As SQL.SQLFieldValues) Implements IDatabaseObject.LoadFields

        pobjProduct = NorthwindDB.Database.Object(NorthwindDB.Products, objFields("ProductID").Value)

        Me.UnitPrice = objFields("UnitPrice").Value
        Me.Quantity = objFields("Quantity").Value
        Me.Discount = objFields("Discount").Value

    End Sub

    Private Function SaveFields() As SQL.SQLFieldValues Implements IDatabaseObject.SaveFields

        Dim objFields As SQL.SQLFieldValues
        objFields = New SQL.SQLFieldValues

        objFields.Add("OrderID", pobjParent.Parent.ID)
        objFields.Add("UnitPrice", Me.UnitPrice)
        objFields.Add("Quantity", Me.Quantity)
        objFields.Add("Discount", Me.Discount)

        Return objFields

    End Function

End Class

By viewing downloads associated with this article you agree to the Terms of Service and the article's licence.

If a file you wish to view isn't highlighted, and is a text file (not binary), please let us know and we'll add colourisation support for it.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

Share

About the Author

Toby Wicks

United States United States
No Biography provided

| Advertise | Privacy | Mobile
Web03 | 2.8.141029.1 | Last Updated 31 Jan 2007
Article Copyright 2005 by Toby Wicks
Everything else Copyright © CodeProject, 1999-2014
Terms of Service
Layout: fixed | fluid