Shape Commands in General
Data shaping defines the columns of a shaped Recordset, the relationships between the entities represented by the columns, and the manner in which the Recordset is populated with data.
A shaped Recordset can consist of the following types of columns.
| Column type | Description |
|---|---|
| data | Fields from a Recordset returned by a query command to a data provider, table, or previously shaped Recordset. |
| chapter | A reference to another Recordset, called a chapter. Chapter columns make it possible to define a parent-child relationship where the parent is the Recordset that contains the chapter column and the child is the Recordset represented by the chapter. |
| aggregate | The value of the column is derived by executing an aggregate function on all the rows or a column of all the rows of a child Recordset. (See Aggregate Functions in the following topic, Aggregate Functions, the CALC Function, and the NEW Keyword.) |
| calculated expression | The value of the column is derived by calculating a Visual Basic for Applications expression on columns in the same row of the Recordset. The expression is the argument to the CALC function. (See Calculated Expression in the following topic, Aggregate Functions, the CALC Function, and the NEW Keyword and in Visual Basic for Applications Functions.) |
| new | Empty, fabricated fields, which can be populated with data at a later time. The column is defined with the NEW keyword. (See NEW keyword in the following topic, Aggregate Functions, the CALC Function, and the NEW Keyword.) |
A shape command can contain a clause that specifies a query command to an underlying data provider that will return a Recordset object. The query's syntax depends on the requirements of the underlying data provider. This will usually be SQL, although ADO does not require the use of any particular query language.
Shape commands can be issued by Recordset objects or by setting the CommandText property of the Command object and then calling the Execute method.
You could use a SQL JOIN clause to relate two tables; however, a hierarchical Recordset can represent the information more efficiently. Each row of a Recordset created by a JOIN repeats information redundantly from one of the tables. A hierarchical Recordset has only one parent Recordset for each of multiple child Recordset objects.
Shape commands can be nested. That is, the parent-command or child-command may itself be another shape command.
The shape provider always returns a client cursor, even when the user specifies a cursor location of adUseServer.
You can access the Recordset components of the shaped Recordset programmatically or through an appropriate visual control.
Microsoft provides a visual tool that generates shape commands (see the Data Environment Designer in the Visual Basic 6 documentation) and another that displays hierarchical cursors (see "Using the Microsoft Hierarchical Flexgrid Control" in the Visual Basic 6 documentation).
For information about navigating a hierarchical Recordset, see Accessing Rows in a Hierarchical Recordset.
For precise information about syntactically correct shape commands, see Formal Shape Grammar.
This section contains the following topics.