An application is a program that calls the ODBC API to access data. Although many types of applications are possible, most fall into three categories, which are used as examples throughout this book.
An important subcategory of generic applications is application development environments, such as PowerBuilder or Microsoft® Visual Basic®. Although the applications constructed with these environments will probably work only with a single DBMS, the environment itself needs to work with multiple DBMSs.
What all generic applications have in common is that they are highly interoperable among DBMSs and they need to use ODBC in a relatively generic manner. For more information about interoperability, see “Choosing a Level of Interoperability” in Chapter 16, “Interoperability.”
The application uses ODBC in such a manner that the application is not tied to any one DBMS, although it might be tied to a limited number of DBMSs that provide similar functionality. Thus, the application developer can sell the application independently from the DBMS. Vertical applications are interoperable when they are developed but are sometimes modified to include noninteroperable code once the customer has chosen a DBMS.
A number of tasks are common to all applications, no matter how they use ODBC. Taken together, they largely define the flow of any ODBC application. The tasks are:
Because the majority of data access work is done with SQL, the primary task for which applications use ODBC is to submit SQL statements and retrieve the results (if any) generated by those statements. Other tasks for which applications use ODBC include determining and adjusting to driver capabilities and browsing the database catalog.