Click here to hide categories Click here to show left categories

User: Home          welcome : Guest          Log In / Register here     




What are relation objects in dataset and how & where to use them

In a DataSet that contains multiple DataTable objects, you can use DataRelation objects to relate one table to another, to navigate through the tables, and to return child or parent rows from a related table. Adding a DataRelation to a DataSet adds, by default, a UniqueConstraint to the parent table and a ForeignKeyConstraint to the child table.

The following code example creates a DataRelation using two DataTable objects in a DataSet. Each DataTable contains a column named CustID, which serves as a link between the two DataTable objects. The example adds a single DataRelation to the Relations collection of the DataSet. The first argument in the example specifies the name of the DataRelation being created. The second argument sets the parent DataColumn and the third argument sets the child DataColumn.

custDS.Relations.Add("CustOrders",
custDS.Tables["Customers"].Columns["CustID"],
custDS.Tables["Orders"].Columns["CustID"]);

OR

private void CreateRelation()
{
// Get the DataColumn objects from two DataTable objects in a DataSet.
DataColumn parentCol;
DataColumn childCol;
// Code to get the DataSet not shown here.
parentCol = DataSet1.Tables["Customers"].Columns["CustID"];
childCol = DataSet1.Tables["Orders"].Columns["CustID"];
// Create DataRelation.
DataRelation relCustOrder;
relCustOrder = new DataRelation("CustomersOrders", parentCol, childCol);
// Add the relation to the DataSet.
DataSet1.Relations.Add(relCustOrder);
}

Share this article   |    Print    |    Article read by 1368 times
Author:
Guest
Guest user is that user who have done some activity on website without login. Activity contains commenting on any article, uploading an image on website etc.
Related Articles:
Related Interview Questions: