This section contains information that is common to the DB2 Connect User's Guide. If you encounter an unfamiliar term or concept in this section, see the DB2 Connect User's Guide.
DB2 Connect lets an application program access data in any DRDA server database. For example, an application running on OS/2 can access data in a DB2 for OS/390 database. You can create new applications, or modify existing applications to run in a DRDA environment. You can also develop applications in one environment and port them to another.
DB2 Connect enables you to use the following items with host database products such as DB2 for OS/390, as long as the item is supported by the host database product:
Some SQL statements differ among relational database products. You may encounter the following situations:
SQL statements in the first two categories are highly portable, but those in the third category will first require changes.
In general, SQL statements in Data Definition Language (DDL) are not as portable as those in Data Manipulation Language (DML).
DB2 Connect accepts some SQL statements that are not supported by DB2 Universal Database. DB2 Connect passes these statements on to the DRDA server.
For information on limits on different platforms, such as the maximum column length, see the sections on SQL Limits and Considerations for Using in the SQL Reference.
If you move a CICS application from OS/390 or VSE to run under another CICS product (for example, CICS for AIX), it can also access the OS/390 or VSE database using DB2 Connect. Refer to the CICS/6000 Application Programming Guide and the CICS Customization and Operation manual for more details.
| Note: | You can use DB2 Connect with a DB2 Universal Database Version 5 database using DRDA, although it would be more efficient to use the DB2 private protocol without DB2 Connect. Most of the incompatibility issues listed in the following sections will not apply if you are using DB2 Connect against a DB2 Universal Database Version 5 database, except in cases where a restriction is due to a limitation of DRDA itself, for example, the non-support of large object (LOB) data types. |
When you program in a DRDA environment, you should consider the following specific factors: