Embedded QUEL
Embedded QUEL (EQUEL) enables you to include QUEL statements in application programs. This guide refers to the programming language of the application as the host language.
For each host language, there is an EQUEL preprocessor. The preprocessor scans your source code for QUEL statements and translates the QUEL statements into the appropriate host language statements. For detailed information about language-dependent topics, see the Embedded QUEL Companion Guide.
In addition to the statements available to you in interactive QUEL, embedded QUEL offers the following features:
Database cursors and transaction processing
Database cursors enable your application to process database rows that fulfill specified search criteria. Transactions help you to preserve database integrity by grouping QUEL statements; if a transaction fails for any reason, the effects of all the statements in the transaction are undone.
Dynamic programming
Your application program can specify portions of many QUEL statements using host variables. The param statement enables database manipulation statements to be built dynamically, in cases where the number and data type of objects to be operated on is not determined until runtime.
Status information
QUEL provides inquiry statements that return detailed information about the database and forms being used by your application program.
Runtime error handling
In EQUEL applications, you can silence error messages and trap errors using an error handler routine. For more information on handling runtime errors, see the Embedded QUEL Companion Guide.
Repeat queries
You can reduce the overhead required to run an embedded query that is executed many times by using repeat queries. The first time a repeat query is executed, the DBMS Server encodes the query. On subsequent executions of the query, this encoding can account for significant performance improvements.