The Data Dictionary

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Attention: The Borland Database Engine (BDE) has been deprecated, so it will not be enhanced. For instance, BDE will never have Unicode support. You should not undertake new development with BDE. Consider migrating your existing database applications from BDE to dbExpress.

When you use the BDE to access your data, your application has access to the Data Dictionary. The Data Dictionary provides a customizable storage area, independent of your applications, where you can create extended field attribute sets that describe the content and appearance of data.

For example, if you frequently develop financial applications, you may create a number of specialized field attribute sets describing different display formats for currency. When you create datasets for your application at design time, rather than using the Object Inspector to set the currency fields in each dataset by hand, you can associate those fields with an extended field attribute set in the data dictionary. Using the data dictionary ensures a consistent data appearance within and across the applications you create.

In a client/server environment, the Data Dictionary can reside on a remote server for additional sharing of information.

To learn how to create extended field attribute sets from the Fields editor at design time, and how to associate them with fields throughout the datasets in your application, see Creating attribute sets for field components. To learn more about creating a data dictionary and extended field attributes with the SQL and Database Explorers, see their respective online help files.

A programming interface to the Data Dictionary is available in the drintf unit (located in the lib directory). This interface supplies the following methods:

Data Dictionary interface

Routine	Use
DictionaryActive	Indicates whether the data dictionary is active.
DictionaryDeactivate	Deactivates the data dictionary.
IsNullID	Indicates whether a given ID is a null ID.
FindDatabaseID	Returns the ID for a database given its alias.
FindTableID	Returns the ID for a table in a specified database.
FindFieldID	Returns the ID for a field in a specified table.
FindAttrID	Returns the ID for a named attribute set.
GetAttrName	Returns the name of an attribute set given its ID.
GetAttrNames	Executes a callback for each attribute set in the dictionary.
GetAttrID	Returns the ID of the attribute set for a specified field.
NewAttr	Creates a new attribute set from a field component.
UpdateAttr	Updates an attribute set to match the properties of a field.
CreateField	Creates a field component based on stored attributes.
UpdateField	Changes the properties of a field to match a specified attribute set.
AssociateAttr	Associates an attribute set with a given field ID.
UnassociateAttr	Removes an attribute set association for a field ID.
GetControlClass	Returns the control class for a specified attribute ID.
QualifyTableName	Returns a fully qualified table name (qualified by user name).
QualifyTableNameByName	Returns a fully qualified table name (qualified by user name).
HasConstraints	Indicates whether the dataset has constraints in the dictionary.
UpdateConstraints	Updates the imported constraints of a dataset.
UpdateDataset	Updates a dataset to the current settings and constraints in the dictionary.

See Also

• BDE-based Architecture
• Tools for Working with the BDE
• Using Transactions with the BDE