By default, dataset fields are dynamic. Their properties and availability are automatically set and cannot be changed in any way. To gain control over a field's properties and events you must create persistent fields for the dataset. Persistent fields let you

• Set or change the field's display or edit characteristics at design time or runtime.
• Create new fields, such as lookup fields, calculated fields, and aggregated fields, that base their values on existing fields in a dataset.
• Validate data entry.
• Remove field components from the list of persistent components to prevent your application from accessing particular columns in an underlying database.
• Define new fields to replace existing fields, based on columns in the table or query underlying a dataset.

At design time, you can—and should—use the Fields editor to create persistent lists of the field components used by the datasets in your application. Persistent field component lists are stored in your application, and do not change even if the structure of a database underlying a dataset is changed. Once you create persistent fields with the Fields editor, you can also create event handlers for them that respond to changes in data values and that validate data entries. All fields used by a single dataset are either persistent or dynamic. You cannot mix field types in a single dataset. If you create persistent fields for a dataset, and then want to revert to dynamic fields, you must remove all persistent fields from the dataset. For more information about dynamic fields, see Dynamic field components. The following topics describe how to use the Fields editor to create or modify the persistent fields in a dataset, and how to work with persistent fields:

• Creating Persistent Fields
• Arranging Persistent Fields
• Defining New Persistent Fields
• Deleting Persistent Field Components
• Setting Persistent Field Properties and Events