Modern Visual Basic applications often use advanced ActiveX components to connect to data sources. These data sources may include Data Access Objects (DAO), Remote Data Objects (RDO), OLE DB providers, such as ActiveX Data Objects (ADO), or the Visual Basic data controls. Using the Active Data Driver for Crystal Reports, you can design reports for your Visual Basic applications that use these same ActiveX data sources. The Active Data Driver also supports Crystal Data Objects (CDO) and the Crystal Data Source Type Library. For more information on RDO, DAO, and ADO, refer to Microsoft documentation. For information on the Data Control, refer to your Visual Basic documentation. For information on CDO, see Crystal Data Object. For information on the Crystal Data Source Type Library, see Crystal Data Source Type Library.
Occasionally, you may also need to create a report when the data source is not actually available at design time. Highly dynamic data may only be available at runtime. In such cases, the Active Data Driver supports the use of Data definition files, tab separated text files that define the fields in a data source but not the actual data.
Normally, developing applications using the Report Designer Component requires designing and saving one or more report files in advance to be accessed by the application at runtime. This process requires that the programmer has access to the data during design time, and that the application, upon installation, also installs whatever database drivers and files are required to make sure the reports can connect to the required data.
An alternative to runtime connectivity, of course, is to save data with the report files. The data is neatly packaged and available whenever the report is requested from your custom application. However, saving data with a report increases the file size of the report, wasting disk space. Furthermore, this technique produces a static report file in which the data cannot be updated without connectivity to the database.
The Crystal Active Data Driver allows you to create report files at design time without specifying an actual data source. Instead, the report is based on a data definition file, an ASCII text file with place holders to represent database fields. At runtime, you add code to your application to specify the actual source of data for the report.
The following topics are discussed in this section:
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