2006-03-22 Senganal T <tsenganal@novell.com>

2006-03-22  Senganal T <tsenganal@novell.com>

	* Test/System.Data/DataColumnTest2.cs :
	* Test/System.Data/ConstraintCollectionTest2.cs :
		- Ensure Constraints are correctly added/removed when Unique
		property is modified.
		- Ensure PrimaryKeyConstraint cannot be removed using Remove ()
		- Ensure DataColumn's Unique Propery is modifed when adding/removing constraint
	* System.Data/DataTable.cs :
		- PrimaryKey : Set the IsPrimaryKey attribute before Removing from collection.
		- RemoveUniqueConstraints : Removed. dead code.
	* System.Data/DataColumn.cs :
		- Unique :
			- If adding/removing constraint fails, retain Unique value
			- Remove redundant code
	* System.Data/UniqueConstraint.cs :
		- SetIsPrimaryKey : Added. Sets the value of IsPrimaryKey.
		- RemoveFromConstraintCollectionCleanup : If constraint is on a single column, then
		set Unique for that column to false.
		- CanRemoveFromCollection : Do not remove constraint, if its a PrimaryKey

svn path=/trunk/mcs/; revision=58301