Analysis of Visual basic Dynamic Data driver

Source: Internet
Author: User
Tags documentation connect

Visual basic applications often use advanced ActiveX components to connect to a data source. These data sources may include the use of data Access Objects (DAO), Remote Data Objects (RDO), OLE DB providers such as ActiveX Data Objects (ADO), COM data providers, crystal Data Objects (CDO) and crystal data source type libraries, or visual Basic Data Control. Using the Visual Basic Dynamic Data driver for the Crystal Report, you can have your application use these same ActiveX data sources. Visual Basic Dynamic Data drivers include:

Crystal Reports database driver for Microsoft Data Access Objects (crdb_dao.dll).

Crystal Reports Database driver for ODBC (Crdb_odbc.dll) for RDO.

Crystal Reports database driver for Microsoft ActiveX Data Objects (crbd_ado.dll).

Crystal Reports Database driver for COM data provider (Crdb_com.dll).

Crystal the Data Object COM DLL (Com32.dll).

Crystal Reports database driver for Crystal Data Object (crdb_cdo.dll).

For more information on using Rdo,dao and ADO, see Microsoft's documentation. For data control information, see your Visual Basic documentation. For information on CDOs, see Crystal Data Objects. For Crystal type library information about the data source, see Crystal Data Source type library.

Sometimes, you may also need to create a data source for a report that is not actually available at design time. High Dynamic Data may only be available at run time. In this case, the field-defined driver (Crdb_fielddef.dll) supports the data definition files that are tab-delimited text files that define the fields of the data source, but not the actual data.

Typically, Visual basic Dynamic Data Driver development uses Report Designer components that require advance design and energy saving for one or more report files to access at run time applications. This process requires programmers to have access to data at design time, which, when installed, also installs any database drivers and file requirements to ensure that reports can connect to the required data.

The connection method to the runtime is the data in the saved report file. The data is packaged beautifully and the existing reports are required from your custom application. However, because the report data saved increases the size of the report file, it wastes disk space. In addition, the technology produces static report files in which the data cannot be updated without connecting to the database.

The field-defined driver allows you to create a report file that does not specify an actual data source at design time. Instead, the report is based on a data definition file, a placeholder ASCII text file, and a database field representative. At run time, you add code to your application to specify the actual source of the report data.

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