ColumnAttribute.Expression Property
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Gets or sets whether a column is a computed column in a database.
public:
property System::String ^ Expression { System::String ^ get(); void set(System::String ^ value); };
public string Expression { get; set; }
member this.Expression : string with get, set
Public Property Expression As String
Property Value
Default = empty.
Examples
[Column(Storage="_UnitPrice", DbType="Money",Expression="UnitPrice + 1.00")]
public System.Nullable<decimal> UnitPrice
{
get
{
return this._UnitPrice;
}
set
{
if ((this._UnitPrice != value))
{
this.OnUnitPriceChanging(value);
this.SendPropertyChanging();
this._UnitPrice = value;
this.SendPropertyChanged("UnitPrice");
this.OnUnitPriceChanged();
}
}
}
<Column(Storage:="_UnitPrice", DbType:="Money NOT NULL", Expression:="UnitPrice + 1.00")> _
Public Property UnitPrice() As Decimal
Get
Return Me._UnitPrice
End Get
Set(ByVal value As Decimal)
If ((Me._UnitPrice = Value) _
= False) Then
Me.OnUnitPriceChanging(Value)
Me.SendPropertyChanging()
Me._UnitPrice = Value
Me.SendPropertyChanged("UnitPrice")
Me.OnUnitPriceChanged()
End If
End Set
End Property
Remarks
Use this property when you use CreateDatabase to define a column as containing computed values.
For example, if you want to create a column defined in SQL as InventoryVal AS UnitPrice * UnitsInStock
, use the following expression string: "UnitPrice * UnitsInStock"
.
Note
LINQ to SQL does not support computed columns as primary keys.
Applies to
Feedback
https://aka.ms/ContentUserFeedback.
Kommer snart: I hele 2024 udfaser vi GitHub-problemer som feedbackmekanisme for indhold og erstatter det med et nyt feedbacksystem. Du kan få flere oplysninger under:Indsend og få vist feedback om