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DataTable.Constraints Property

Gets the collection of constraints maintained by this table.

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

member Constraints : ConstraintCollection

Property Value

Type: System.Data.ConstraintCollection
A ConstraintCollection that contains the collection of Constraint objects for the table. An empty collection is returned if no Constraint objects exist.

A ForeignKeyConstraint restricts the action performed when a value in a column (or columns) is either deleted or updated. Such a constraint is intended to be used with primary key columns. In a parent/child relationship between two tables, deleting a value from the parent table can affect the child rows in one of the following ways.

  • The child rows can also be deleted (a cascading action).

  • The values in the child column (or columns) can be set to null values.

  • The values in the child column (or columns) can be set to default values.

  • An exception can be generated.

A UniqueConstraint becomes active when attempting to set a value in a primary key to a non-unique value.

The following example adds a ForeignKeyConstraint to the collection of constraints.

No code example is currently available or this language may not be supported.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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