Monday, April 27, 2009

Limiting records with parameters

When the provider on the application server represents the results of a table component, you can use Params property to limit the records that are provided to the Data property.
Each parameter name must match the name of a field in the TTable component on the application server. The provider component on the application server sends only those records whose values on the corresponding fields match the values assigned to the parameters.

For example, consider a client application that displays the orders for a single customer. When the user identifies the customer, the client dataset sets its Params property to include a single parameter named CustID (or whatever field in the server table is called) whose value identifies the customer whose orders it will display. When the client dataset requests data from the application server, it passes this parameter value. The application server then sends only the records for the identified customer. This is more efficient than letting the application server send all the orders records to the client application and then filtering the records on the client side.

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