You create an application by using the Microsoft .NET Framework 3.5 and Microsoft ADO.NET.
You write the following code segment.
DataTable tblInvDet = new DataTable("InvoiceDetail");
DataColumn colInvNo = tblInvDet.Columns.Add("InvNo", typeof(string));
DataColumn colItemNo = tblInvDet.Columns.Add("ItemNo", typeof(int));
You need to ensure that the corresponding values in the InvNo DataColumn and the ItemNo DataColumn form a unique pair.
Which code segment should you use?
A.
colInvNo.Unique = true;
colItemNo.Unique = true;
B.
UniqueConstraint con = new UniqueConstraint("UnqCol", new DataColumn[] { colInvNo, colItemNo }, false);
tblInvDet.Constraints.Add(con);
C.
UniqueConstraint con1 = new UniqueConstraint("UnqCol1", colInvNo, true);
UniqueConstraint con2 = new UniqueConstraint("UnqCol2", colItemNo, true);
tblInvDet.Constraints.Add(con1);
tblInvDet.Constraints.Add(con2);
D.
UniqueConstraint con1 = new UniqueConstraint("UnqCol1", colInvNo, false);
UniqueConstraint con2 = new UniqueConstraint("UnqCol2", colItemNo, false);
tblInvDet.Constraints.AddRange(new UniqueConstraint[] { con1,con2});