Chapter 17: Defining DataWindow Objects

Selecting a data source

The data source you choose determines how you select the data that will be used in the DataWindow object.

About the term data source The term data source used here refers to how you use the DataWindow painter to specify the data to retrieve into the DataWindow object.

If the data is in the database

If the data for the DataWindow object will be retrieved from a database, choose one of the types of data source listed in Table 17-1.

**Table 17-1: Types of data source to be used in a DataWindow object**
Data source	Use when
Quick Select	The data is from a single table (or from tables that are related through foreign keys) and you need to choose only columns, selection criteria, and sorting.
SQL Select	You want more control over the SQL SELECT statement generated for the data source or your data is from tables that are not connected through a key. For example, you need to specify grouping, computed columns, or retrieval arguments within the SQL SELECT statement.
Query	The data has been defined as a query.
Stored Procedure	The data is defined in a stored procedure.

If the data is not in a database

Select the External data source if:

The DataWindow object will be populated programmatically
Data will be imported from a DDE application
Data will be imported from an external file, such as a tab-separated text file (TXT file) or a dBASE file (DBF file)

PocketBuilder

After you choose a data source in the various DataWindow wizards, you specify the data. The data source you choose determines what displays in the wizards and how you define the data.

Why use a DataWindow if the data is not from a DBMS

Even when the data does not come from the database, there are many times when you want to take advantage of the intelligence of a DataWindow object:

Data Validation You have full access to validation rules for data.
Display Formats You can use any existing display formats to present the data, or create your own.
Edit Styles You can use any existing edit styles, such as radio buttons and edit masks, to present the data, or create your own.

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