Designing and Programming the Application
The first step in using Progress/ESQL is to design and program your ESQL application. An ESQL application consists of the database(s) you use to store data and one or more ESQL source files. An ESQL source file is a program written in C that contains ESQL statements and ESQL-LIB function calls.
Figure 1–4 shows a fragment of an ESQL source file that contains ESQL statements. The bold text shows the ESQL-LIB function calls.
Figure 1–4: ESQL Sample Source File Fragment
Consider the following options when designing your application:
- Can you define all SQL statements at compile time or do you need to allow for SQL requests known only at run-time? To specify requests at run time, use dynamic ESQL. Otherwise, static ESQL is sufficient.
- Do you need to specify repeated run-time SQL requests that differ only in the parameter values used for selection or input criteria? If so, you can implement dynamic ESQL calls with parameter marker capability.
- Does your application have specialized signal or memory requirements, and if so, does it run on a single platform or on a network? You can meet your requirements by planning for a small or large client environment. Your choice might affect how you specify your own functions and signal processing requirements (in a UNIX environment).
For more information on designing and coding your ESQL application, see Programming with ESQL."
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