DataSourceParameter

Overview

A DataSourceParameter controls certain aspects of a DataSource during runtime (e.g. the filename of a DataSourceCsv, the SELECT statement of a DataSourceOdbc).

DataSourceParameters provide an elegant way to implement dynamic DataSources, without modifying the DataSource definition. They can be used to parameterize ODBC DataSources (DataSourceOdbc) and file-based DataSources (DataSourceCsv, DataSourceXml).

A typical scenario is the use of DataSourceParameters in the SQL SELECT statement of an DataSourceOdbc. By this technique TFORMer can be instructed to fetch only specific records of a table or to change the sorting order via parameters.

DataSourceParameters can also be used in ComputedFields.

Example

Sample for using a data source parameter named parOrder:

Assume we have a Parameter named parOrder and want to use it in an SQL select statement.

  SELECT * FROM tblOrders WHERE Order = [GetDSParam("parOrder")] 

Providing a parameter value of 4711 would result in the following statement:

  SELECT * FROM tblOrders WHERE Order = 4711