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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
' ___________________________________________________
'
'  � Hi-Integrity Systems 2007. All rights reserved.
'  www.hisystems.com.au - Toby Wicks
' ___________________________________________________
'

Option Strict On
Option Explicit On 

''' --------------------------------------------------------------------------------
''' <summary>
''' This class can be used in conjunction with the DatabaseObjects class to simplify
''' the process of using the DatabaseObjects library. This class implements the 
''' IDatabaseObject interface and provides the basic "plumbing" code required by the 
''' interface. For this reason, inheriting from this class is preferable to 
''' implementing the IDatabaseObject interface directly.
''' </summary>
''' --------------------------------------------------------------------------------
''' 
Public MustInherit Class DatabaseObject
    Implements IDatabaseObject

    Private pbIsSaved As Boolean
    Private pobjDistinctValue As Object
    Private pobjParentCollection As DatabaseObjects

    ''' --------------------------------------------------------------------------------
    ''' <summary>
    ''' Initializes a new DatabaseObject with the parent collection that this object is 
    ''' associated with.
    ''' </summary>
    ''' 
    ''' <example> 
    ''' <code>
    ''' 'Code from a class that has inherited from DatabaseObjects
    ''' 'So that this object has a reference to the parent
    ''' Protected Overrides Function ItemInstance() As DatabaseObjects.IDatabaseObject
    ''' 
    '''     Return New Product(Me)
    ''' 
    ''' End Function
    ''' </code>
    ''' </example>
    ''' --------------------------------------------------------------------------------
    ''' 
    Protected Sub New(ByVal objParentCollection As DatabaseObjects)

        If objParentCollection Is Nothing Then
            Throw New ArgumentNullException
        End If

        pobjParentCollection = objParentCollection

    End Sub

    ''' --------------------------------------------------------------------------------
    ''' <summary>
    ''' Returns the parent collection (DatabaseObjects instance) that this object is 
    ''' associated with.
    ''' </summary>
    ''' --------------------------------------------------------------------------------
    ''' 
    Protected ReadOnly Property ParentCollection() As DatabaseObjects
        Get

            Return pobjParentCollection

        End Get
    End Property

    ''' --------------------------------------------------------------------------------
    ''' <summary>
    ''' Returns the database associated with this object.
    ''' </summary>
    ''' --------------------------------------------------------------------------------
    '''
    Protected ReadOnly Property ParentDatabase() As Database
        Get

            Return pobjParentCollection.Database

        End Get
    End Property

    ''' --------------------------------------------------------------------------------
    ''' <summary>
    ''' Extracts the fields to save to the database from the objItem.SaveFields function.
    ''' The fields are then written to the database using either an SQL INSERT or UPDATE 
    ''' depending on whether the object has already been saved. If the collection has 
    ''' implemented IDatabaseObjects.KeyFieldName then objItem's key is also validated to
    ''' ensure it is not null and unique within the collection.
    ''' If the parent collection has implemented Subset then this object should exist 
    ''' within the parent collection. If not, a duplicate key error may occur if the key 
    ''' is being used in another subset in the same table. If a record is being amended 
    ''' (MyBase.IsSaved is True) then the function will "AND" the parent collection's 
    ''' Subset conditions and the DistinctValue value to create the WHERE clause in the 
    ''' UPDATE statement. Therefore, the combination of the IDatabaseObjects.Subset and 
    ''' IDatabaseObject.DistinctValue conditions MUST identify only one record in the 
    ''' table. Otherwise multiple records will be updated with the same data. If data is
    ''' only inserted and not amended (usually a rare occurance) then this requirement 
    ''' is unnecessary.
    ''' </summary>
    ''' 
    ''' <example> 
    ''' <code>
    ''' 'Make the inherited "Protected Sub Save" public
    ''' Public Overrides Sub Save()
    ''' 
    '''     MyBase.Save()
    ''' 
    ''' End Sub
    ''' </code>
    ''' </example>    
    ''' --------------------------------------------------------------------------------
    ''' 
    Protected Overridable Sub Save()

        ParentDatabase.ObjectSave(ParentCollection, Me)

    End Sub

    ''' --------------------------------------------------------------------------------
    ''' <summary>
    ''' Returns the distinct value that uniquely identifies this object in the 
    ''' database. If a new object is saved or an existing object is loaded then this 
    ''' property is automatically set by the library. 
    ''' Typically, this is the value of an identity or auto increment database field.
    ''' </summary>
    ''' --------------------------------------------------------------------------------
    '''
    Protected Overridable Property DistinctValue() As Object Implements IDatabaseObject.DistinctValue
        Get

            Return pobjDistinctValue

        End Get

        Set(ByVal Value As Object)

            pobjDistinctValue = Value

        End Set
    End Property

    ''' --------------------------------------------------------------------------------
    ''' <summary>
    ''' Returns whether this object has been saved to the database. If a new object is 
    ''' saved (which uses an auto increment field) or an existing object is loaded then 
    ''' this property is automatically set to true by the library.
    ''' </summary>
    ''' --------------------------------------------------------------------------------
    '''
    Protected Overridable Property IsSaved() As Boolean Implements IDatabaseObject.IsSaved
        Get

            Return pbIsSaved

        End Get

        Set(ByVal Value As Boolean)

            pbIsSaved = Value

        End Set
    End Property

    ''' --------------------------------------------------------------------------------
    ''' <summary>
    ''' Should copy the database fields from objFields to this object's variables. 
    ''' objFields is populated with all of the fields from the associated record.
    ''' </summary>
    ''' 
    ''' <example> 
    ''' <code>
    ''' Protected Overrides Sub LoadFields(ByVal objFields As DatabaseObjects.SQL.SQLFieldValues)
    ''' 
    '''     pstrCode = objFields("ProductCode").Value
    '''     pstrDescription = objFields("ProductDescription").Value
    ''' 
    ''' End Sub
    ''' </code>
    ''' </example>
    ''' --------------------------------------------------------------------------------
    ''' 
    Protected MustOverride Sub LoadFields(ByVal objFields As SQL.SQLFieldValues) Implements IDatabaseObject.LoadFields


    ''' --------------------------------------------------------------------------------
    ''' <summary>
    ''' Should return an SQLFieldValues object populated with the  
    ''' fields to be written to the database. The first argument of the 
    ''' SQLFieldValues.Add function is the database field name, the second is the 
    ''' field's value.
    ''' </summary>
    ''' 
    ''' <example> 
    ''' <code>
    ''' Protected Overrides Function SaveFields() As DatabaseObjects.SQL.SQLFieldValues
    ''' 
    '''     SaveFields = New SQL.SQLFieldValues
    '''     SaveFields.Add("ProductCode", pstrCode)
    '''     SaveFields.Add("ProductDescription", pstrDescription)
    ''' 
    ''' End Function
    ''' </code>
    ''' </example>
    ''' --------------------------------------------------------------------------------
    ''' 
    Protected MustOverride Function SaveFields() As SQL.SQLFieldValues Implements IDatabaseObject.SaveFields

End Class

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Toby Wicks

United States United States
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