Articolo
11/18/2011

ColumnAttribute Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Associates a class with a column in a database table.

Inheritance Hierarchy

System.Object
  System.Attribute
    System.Data.Linq.Mapping.DataAttribute
      System.Data.Linq.Mapping.ColumnAttribute

Namespace: System.Data.Linq.Mapping
Assembly: System.Data.Linq (in System.Data.Linq.dll)

Syntax

'Declaration
<AttributeUsageAttribute(AttributeTargets.Property Or AttributeTargets.Field, AllowMultiple := False)> _
Public NotInheritable Class ColumnAttribute _
    Inherits DataAttribute

[AttributeUsageAttribute(AttributeTargets.Property|AttributeTargets.Field, AllowMultiple = false)]
public sealed class ColumnAttribute : DataAttribute

The ColumnAttribute type exposes the following members.

Constructors

	Name	Description
	ColumnAttribute	Initializes a new instance of the ColumnAttribute class.

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Properties

	Name	Description
	AutoSync	Gets or sets the AutoSync enumeration.
	CanBeNull	Gets or sets whether a column can contain null values.
	DbType	Gets or sets the type of the database column.
	Expression	Gets or sets whether a column is a computed column in a database.
	IsDbGenerated	Gets or sets whether a column contains values that the database auto-generates.
	IsDiscriminator	Gets or sets whether a column contains a discriminator value for a LINQ to SQL inheritance hierarchy.
	IsPrimaryKey	Gets or sets whether this class member represents a column that is part or all of the primary key of the table.
	IsVersion	Gets or sets whether the column type of the member is a database timestamp or version number.
	Name	Gets or sets the name of a column. (Inherited from DataAttribute.)
	Storage	Gets or sets a private storage field to hold the value from a column. (Inherited from DataAttribute.)
	UpdateCheck	Gets or sets how LINQ to SQL approaches the detection of optimistic concurrency conflicts.

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Methods

	Name	Description
	Equals	Infrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
	GetHashCode	Returns the hash code for this instance. (Inherited from Attribute.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	Match	When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Remarks

Use this attribute to designate a member of an entity class to represent a column in a database table. You can apply this attribute to any field or property that is public, private, or internal.

Only those entity class members identified as columns are persisted when LINQ to SQL saves changes to the database.

Use commas to separate multiple properties on the attribute.

Topic	Location
Attribute-Based Mapping (LINQ to SQL)	LINQ to SQL
How to: Represent Columns as Class Members (LINQ to SQL)	LINQ to SQL
The LINQ to SQL Object Model	LINQ to SQL
Attribute-Based Mapping (LINQ to SQL)	LINQ to SQL
How to: Represent Columns as Class Members (LINQ to SQL)	LINQ to SQL
The LINQ to SQL Object Model	LINQ to SQL

Examples

<Table(Name:="Employees")>  _
Public Class Employees
    Private _LastName As String
    ' …
    <Column(Storage:="_LastName", DbType:="NVarChar(20) NOT NULL", _
        CanBeNull:=false)> _
    Public Property LastName() As String
        Get
            Return Me._LastName
        End Get
        Set
            If ((Me._LastName = value) _
                = false) Then
                Me.OnPropertyChanging("LastName")
                Me._LastName = value
                Me.OnPropertyChanged("LastName")
            End If
        End Set
    End Property
End Class

[Table(Name="Employees")]
public class Employees
{
    private string _LastName;    
    // …
    [Column(Storage="_LastName", DbType="NVarChar(20) NOT NULL", 
        CanBeNull=false)]
    public string LastName
    {
        get
        {
            return this._LastName;
        }
        set
        {
            if ((this._LastName != value))
            {
                this.OnPropertyChanging("LastName");
                this._LastName = value;
                this.OnPropertyChanged("LastName");
            }
        }
    }
}

Version Information

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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