Operation of Non-Parameterized Commands

For non-parameterized commands, all of the provider commands are executed and the Recordsets are created during command execution. If the command is executed synchronously, all of the Recordsets will be fully populated. If an asynchronous population mode was selected, the populated state of the Recordsets will depend on the population mode and the size of the Recordsets.

For example, the parent-command could return a Recordset of customers for a company from a Customers table, and the child-command could return a Recordset of orders for all customers from an Orders table.

SHAPE {SELECT * FROM Customers} 
   APPEND ({SELECT * FROM Orders} AS chapOrders 
   RELATE customerID TO customerID)

For non-parameterized parent-child relationships, each parent and child Recordset object must have a column in common to associate them. The columns are named in the RELATE clause, parent-column first and then child-column. The columns may have different names in their respective Recordset objects but must refer to the same information in order to specify a meaningful relation. For example, the Customers and Orders Recordset objects could both have a customerID field. Because the membership of the child Recordset is determined by the provider command, it is possible for the child Recordset to contain orphaned rows. These orphaned rows are inaccessible without further reshaping.

Data shaping appends a chapter column to the parent Recordset. The values in the chapter column are references to rows in the child Recordset, which satisfy the RELATE clause. That is, the same value is in the parent-column of a given parent row as is in the child-column of all the rows of the chapter child. When multiple TO clauses are used in the same RELATE clause, they are implicitly combined using an AND operator. If the parent columns in the relate clause do not constitute a key to the parent Recordset, a single child row may have multiple parent rows.

When you access the reference in the chapter column, ADO automatically retrieves the Recordset represented by the reference. Note that in a non-parameterized command, although the entire child Recordset has been retrieved, the chapter only presents a subset of rows.

If the appended column has no chapter-alias, a name will be generated for it automatically. A Field object for the column will be appended to the Recordset object's Fields collection, and its data type will be adChapter.

For information about navigating a hierarchical Recordset, see Accessing Rows in a Hierarchical Recordset.

See Also

Data Shaping | Formal Shape Grammar | Shape Commands in General