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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>
''' Extends the capabilities of the DatabaseObject by providing a set of routines 
''' that lock and unlock this object for exclusive access for a particular user.
''' When Lock() is called a record is written to the lock table which includes the
''' object's associated table name, the object's distinct value and the user ID
''' specified in the DatabaseObjectLockController. When Unlock() is called this 
''' record is deleted. If another or the current user has locked the object then the 
''' IsLocked property will return true.
''' The DatabseObjects library does not inhibit the loading and/or saving of any 
''' locked objects.
''' </summary>
''' --------------------------------------------------------------------------------
''' 
Public MustInherit Class DatabaseObjectLockable
    Inherits DatabaseObject
    Implements IDatabaseObjectLockable

    Private pobjLockController As DatabaseObjectLockController

    ''' --------------------------------------------------------------------------------
    ''' <summary>
    ''' Initializes a new DatabaseObject with the parent collection that this object is 
    ''' associated with and the lock controller to be used with this object.
    ''' </summary>
    ''' --------------------------------------------------------------------------------
    Protected Sub New(ByVal objParent As DatabaseObjects, ByVal objLockController As DatabaseObjectLockController)

        MyBase.New(objParent)

        If objLockController Is Nothing Then
            Throw New ArgumentNullException
        End If

        pobjLockController = objLockController

    End Sub

    ''' --------------------------------------------------------------------------------
    ''' <summary>
    ''' Indicates whether the current object is Locked either by the current user or 
    ''' another user.
    ''' </summary>
    ''' --------------------------------------------------------------------------------
    Public ReadOnly Property IsLocked() As Boolean Implements IDatabaseObjectLockable.IsLocked
        Get

            Return pobjLockController.IsLocked(DirectCast(MyBase.ParentCollection, IDatabaseObjects).TableName, Me)

        End Get
    End Property

    ''' --------------------------------------------------------------------------------
    ''' <summary>
    ''' Returns the user identifier that currently has the object locked. Throws an 
    ''' exception if the object is not locked by a user.
    ''' </summary>
    ''' --------------------------------------------------------------------------------
    Protected ReadOnly Property LockedByUserID() As String Implements IDatabaseObjectLockable.LockedByUserID
        Get

            Return pobjLockController.LockedByUserID(DirectCast(MyBase.ParentCollection, IDatabaseObjects).TableName, Me)

        End Get
    End Property

    ''' --------------------------------------------------------------------------------
    ''' <summary>
    ''' Locks the current object. Throws an exception if the object is already locked.
    ''' </summary>
    ''' --------------------------------------------------------------------------------
    Public Sub Lock() Implements IDatabaseObjectLockable.Lock

        pobjLockController.Lock(DirectCast(MyBase.ParentCollection, IDatabaseObjects).TableName, Me)

    End Sub

    ''' --------------------------------------------------------------------------------
    ''' <summary>
    ''' UnLocks the current object. Throws an exception if the object is not locked.
    ''' </summary>
    ''' --------------------------------------------------------------------------------
    Public Sub UnLock() Implements IDatabaseObjectLockable.UnLock

        pobjLockController.UnLock(DirectCast(MyBase.ParentCollection, IDatabaseObjects).TableName, Me)

    End Sub

    ''' --------------------------------------------------------------------------------
    ''' <summary>
    ''' Returns whether the current user has the object locked.
    ''' </summary>
    ''' --------------------------------------------------------------------------------
    Public ReadOnly Property IsLockedByCurrentUser() As Boolean Implements IDatabaseObjectLockable.IsLockedByCurrentUser
        Get

            Return pobjLockController.IsLockedByCurrentUser(DirectCast(MyBase.ParentCollection, IDatabaseObjects).TableName, Me)

        End Get
    End Property

End Class

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Toby Wicks

United States United States
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Web01 | 2.8.140926.1 | Last Updated 31 Jan 2007
Article Copyright 2005 by Toby Wicks
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