Programmatic Access
 |  |  |  |
 |
| |||||||||
 |
| ||
If you’re a programmer, you’ll be happy to hear that you have full programmatic access to Crystal Reports and many of the databases used with Crystal. Collaboration with Microsoft has provided a path to that company’s concept of Universal Data Access to data in the business enterprise. Acronyms abound here and include methodologies such as DAO, RDO, and ADO. Luckily, they all accomplish the same task—access to stored data from external programs. Here’s a quick overview of each:
DAO Data Access Objects (DAO) is an older technology that uses the JET Engine and ODBC to connect to a data source. Although Microsoft is phasing out this programmatic methodology, you will notice at the top of the list of available data sources in the Database Expert shown in Figure 10.28 that one of the ways you can connect to Microsoft Excel and Microsoft Access is using DAO. The Database Expert shows the programming technology in parentheses, while the name of the supported database application appears to the left and is the focus. This architecture is sometimes referred to as a one-tier architecture based on its simplicity and lack of ability to be extended to other types of data sources.
RDO Remote Data Objects (RDO) is more recent than DAO and is sometimes referred to as a two-tier architecture. Programmers can use RDO with the Enterprise Edition of Visual Basic to connect to remote databases using ODBC. In the list of data sources shown in Figure 10.28, note that about two-thirds of the way down you’ll find ODBC (RDO) data sources listed. Microsoft is also phasing out this programmatic methodology, but Crystal Reports fully supports existing applications and databases that use it, especially since it is so prevalent in today’s business world.
Figure 10.28. DAO in the Database Expert
ADO ActiveX Data Objects (ADO) is a programming interface into the world of Microsoft’s OLE DB data access methodology. Its goal is to provide programmatic access to a wide variety of data while minimizing the complexity of dealing with different databases. A standard set of objects provides fast, easy access to underlying databases. ADO is fairly lightweight and can be used for desktop programming and Internet programming. Take a look back at Figure 10.27 and notice that just short of the bottom you’ll see an option to connect to an OLE DB (ADO) data source. This is the currently blessed Microsoft methodology for accessing databases from within code.
Part 4 of this book, “Application Development with Crystal Reports,” goes into depth on the topic of programming Crystal Reports without using the user interface. It provides everything you need to know to use code to manipulate Crystal Reports and its data for report delivery on the desktop and the Web.
| ||
 | |
| Use of content on this site is expressly subject to the restrictions set forth in the Membership Agreement | |
| Conello © 2000-2003 Feedback | |
EAN: 2147483647
Pages: 217