Micro Focus Visual COBOL 2.3 for Visual Studio 2012 > Programming > Data Access > Database Connectors > Database Connectors User's Guide > Database Connectors Overview > How Database Connectors Works > Summary

Summary

Restriction: This topic applies only when a Database Connectors license has been installed via the Micro Focus License Management System.

Database Connectors ensures that all database changes are immediately available to your COBOL program. It also ensures that all data updates to your COBOL program are immediately reflected in the database.

User's World

After your XFDs are generated, you can switch to a different RDBMS simply by setting DEFAULT_HOST to point to the new RDBMS. No recompiling is necessary.

Because Database Connectors accesses the database through its native engine, the full relational integrity of the database is maintained. The COBOL program need not be concerned about such things as enforcing relationships between keys and foreign keys on tables or constraints on field relationships and contents.

If you have specified that a file is to reside on a RDBMS by setting either DEFAULT_HOST or filename_HOST, an OPEN OUTPUT filename statement in your COBOL program generates a CREATE TABLE filename function on the specified host database. Appropriate permissions are granted based on login and password and on set access parameters. (For details, see the Contents pane to find the appendix specific to your RDBMS.) For large tables, your systems database administrator can create the table and indexes for you. Databases offer many methods for creating tables that may improve performance for large tables, such as spreading the table across multiple hard drives or storing the data and the indexes on different drives.

Note: Database Connectors uses a specific naming convention for indexes it creates. Indexes created with Database Connectors use the i<TABLENAME>_<key value> convention. If you are using indexes created outside of the Database Connectors application, you must ensure that the index names match the Database Connectors naming convention.

Changes to the way a database functions should be carefully considered and tested before being fully implemented. If a database violation occurs, the engine detects it, and Database Connectors returns an I/O error condition to the COBOL program. The program can, if desired, call a standard COBOL library routine for an extended error description.

It is possible that there are library routines that do not work with or do not make sense to use with some of the Database Connectors interfaces. To find out if that is the case with your Database Connectors interface, look in the Common Questions and Answers section of the appendix specific to your interface.