Answer / swapna

ADO.NET provides DataRelation object to set relation
between two columns.It helps to enforce the following
constraints,a unique constraint, which guarantees that a
column in the table contains no duplicates and a foreign-
key constraint,which can be used to maintain referential
integrity.

A unique constraint is implemented either by simply setting
the Unique property of a data column to true, or by adding
an instance of the UniqueConstraint class to the
DataRelation object's ParentKeyConstraint.

As part of the foreign-key constraint, you can specify
referential integrity rules that are applied at three
points,when a parent record is updated,when a parent record
is deleted and when a change is accepted or rejected.

Answer / muthu kumar

DataSet d = new DataSet();
DataColumn parentDC = new
DataColumn(d.Tables["parentTable"].Columns["id"]);
DataColumn childDC = new
DataColumn(d.Tables["ChildTable"].Columns["id"]);
DataRelation ds = new DataRelation("relation name",
parentDC, childDC);
d.Relations.Add(ds);

Answer / ganesh

the only option is foreign key

can we have multiple datatables in a datareader ?

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