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Option Strict Off
Option Explicit On
Imports DatabaseObjects
Imports System.Collections
Public Class Suppliers
Implements IDatabaseObjects
Implements IEnumerable
Default Public ReadOnly Property Item(ByVal strName As String) As Supplier
Get
Return NorthwindDB.Database.ObjectByKey(Me, strName)
End Get
End Property
Default Public ReadOnly Property Item(ByVal intOrdinal As Integer) As Supplier
Get
Return NorthwindDB.Database.ObjectByOrdinal(Me, intOrdinal)
End Get
End Property
Public ReadOnly Property Count() As Integer
Get
Return NorthwindDB.Database.ObjectsCount(Me)
End Get
End Property
Public Function Exists(ByVal strName As String) As Boolean
Return NorthwindDB.Database.ObjectExists(Me, strName)
End Function
Public Sub Delete(ByRef objSupplier As Supplier)
If objSupplier.IsDeletable Then
NorthwindDB.Database.ObjectDelete(Me, objSupplier)
Else
Throw New ApplicationException("Supplier Undeletable: " & objSupplier.Name)
End If
End Sub
Private Function DistinctFieldAutoIncrements() As Boolean Implements IDatabaseObjects.DistinctFieldAutoIncrements
Return True
End Function
Private Function DistinctFieldName() As String Implements IDatabaseObjects.DistinctFieldName
Return "SupplierID"
End Function
Private Function ItemInstance() As IDatabaseObject Implements IDatabaseObjects.ItemInstance
Return New Supplier
End Function
Private Function KeyFieldName() As String Implements IDatabaseObjects.KeyFieldName
Return "CompanyName"
End Function
Private Function OrderBy() As SQL.SQLSelectOrderByFields Implements IDatabaseObjects.OrderBy
Dim objOrderByFields As SQL.SQLSelectOrderByFields = New SQL.SQLSelectOrderByFields
objOrderByFields.Add("CompanyName", SQL.OrderBy.Ascending)
Return objOrderByFields
End Function
Private Function Subset() As SQL.SQLConditions Implements IDatabaseObjects.Subset
'Dim objConditions As SQL.SQLConditions = New SQL.SQLConditions
'objConditions.Add("CompanyName", SQL.ComparisonOperator.Like, "M%")
'objConditions.AddLogicalOperator(SQLSelect.LogicalOperator.Or)
'objConditions.Add("CompanyName", SQL.ComparisonOperator.Like, "N%")
'Return objConditions
End Function
Private Function TableName() As String Implements IDatabaseObjects.TableName
Return "Suppliers"
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
Private Function GetEnumerator() As System.Collections.IEnumerator Implements System.Collections.IEnumerable.GetEnumerator
Return NorthwindDB.Database.ObjectsList(Me).GetEnumerator
End Function
End Class
Public Class Supplier
Implements IDatabaseObject
Private pintID As Integer
Private pstrName As String
Friend ReadOnly Property ID() As Integer
Get
'Friend will allow public access within the NorthwindDB project but will be
'private outside of the NorthwindDB project
Return pintID
End Get
End Property
Public Property Name() As String
Get
Return pstrName
End Get
Set(ByVal Value As String)
pstrName = Value.Trim
End Set
End Property
Public ReadOnly Property IsDeletable() As Boolean
Get
'This checks the Products table to see if there are any references to this Supplier.
'If there are then this supplier cannot be deleted.
Dim objReader As IDataReader
Dim objConnection As IDbConnection
Dim objSelect As SQL.SQLSelect = New SQL.SQLSelect
With objSelect
.Fields.Add("", SQL.AggregateFunction.Count)
.Tables.Add("Products")
.Where.Add("SupplierID", SQL.ComparisonOperator.EqualTo, pintID)
objConnection = NorthwindDB.CreateConnection
objConnection.Open()
With objConnection.CreateCommand
.CommandText = objSelect.SQL
objReader = .ExecuteReader
End With
objReader.Read()
IsDeletable = (objReader(0) = 0)
objReader.Close()
objConnection.Close()
End With
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()
NorthwindDB.Database.ObjectSave(NorthwindDB.Suppliers, Me)
End Sub
Private Sub LoadFields(ByVal objFields As SQL.SQLFieldValues) Implements IDatabaseObject.LoadFields
pstrName = objFields("CompanyName").Value
End Sub
Private Function SaveFields() As SQL.SQLFieldValues Implements IDatabaseObject.SaveFields
Dim objFields As SQL.SQLFieldValues = New SQL.SQLFieldValues
objFields.Add("CompanyName", pstrName)
Return objFields
End Function
End Class
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