At design time you can create or edit connection parameters in three ways:

• Use the Database Explorer to create or modify BDE aliases, including parameters. For more information about these utilities, see their online Help files.
• Double-click the Params property in the Object Inspector to invoke the String List editor.
• Double-click a database component in a data module or form to invoke the Database Properties editor.

All of these methods edit the Params property for the database component. Params is a string list containing the database connection parameters for the BDE alias associated with a database component. Some typical connection parameters include path statement, server name, schema caching size, language driver, and SQL query mode. 

When you first invoke the Database Properties editor, the parameters for the BDE alias are not visible. To see the current settings, click Defaults. The current parameters are displayed in the Parameter overrides memo box. You can edit existing entries or add new ones. To clear existing parameters, click Clear. Changes you make take effect only when you click OK. 

At runtime, an application can set alias parameters only by editing the Params property directly.