Using Implicit Connections
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No matter what data access mechanism you are using, you can always create the connection component explicitly and use it to manage the connection to and communication with a database server. For BDE-enabled and ADO-based datasets, you also have the option of describing the database connection through properties of the dataset and letting the dataset generate an implicit connection. For BDE-enabled datasets, you specify an implicit connection using the DatabaseName property. For ADO-based datasets, you use the ConnectionString property.
When using an implicit connection, you do not need to explicitly create a connection component. This can simplify your application development, and the default connection you specify can cover a wide variety of situations. For complex, mission-critical client/server applications with many users and different requirements for database connections, however, you should create your own connection components to tune each database connection to your application's needs. Explicit connection components give you greater control. For example, you need to access the connection component to perform the following tasks:
- Customize database server login support. (Implicit connections display a default login dialog to prompt the user for a user name and password.)
- Control transactions and specify transaction isolation levels.
- Execute SQL commands on the server without using a dataset.
- Perform actions on all open datasets that are connected to the same database.
In addition, if you have multiple datasets that all use the same server, it can be easier to use an connection component, so that you only have to specify the server to use in one place. That way, if you later change the server, you do not need to update several dataset components: only the connection component.