When master-detail relations are defined between tables in a C1ExpressConnection component, they can be used to build data-bound master-detail forms and to navigate parent/child rows programmatically (with GetChildRow(s)/GetParentRow(s) methods). To create a master-detail relation, check the Master-detail check box in Relations editor.

Having a master-detail relation, you can bind two data-aware controls, one to the master and the other to the detail, and the detail control will follow the master, will be automatically populated with child rows of the parent row on which the master is currently positioned. In presence of master-detail relations, the DataMember combo box of a data-aware control shows tables participating in the master-detail hierarchy preceding with underscore, whereas the same tables regarded as standalone (not restricted by master-detail relations) are shown without underscore. For example, if you have a "Customers – Orders" relation, this is how you can bind a master and a detail grid:

To write code in Visual Basic

ParentGrid1.DataMember = "_Customers"
ParentGrid1.DataSource = C1ExpressConnection1
ChildGrid1.DataMember = "_Customers.Customers-Orders"
ChildGrid1.DataSource = C1ExpressConnection1

To write code in C#

parentGrid1.DataMember = "_Customers";
parentGrid1.DataSource = C1ExpressConnection1;
childGrid1.DataMember = "_Customers.Customers-Orders";
childGrid1.DataSource = C1ExpressConnection1;