Some of the differences between DB2® for UNIX™ / Windows™ and DB2 for OS/400® are:
- There is only one database on a system; you can not create two
instances on the same database server. The database is a single system-wide
database. The database name used for the connect statement is the
name of the system. Schemas (Collections) can be used to manage different
logical databases on the same OS/400 machine.
- There is no TABLESPACE concept on DB2 for iSeries®. All the storage is
controlled by the database manager and operating system.
- The identity column is not supported (for serial emulation).
- The SET SCHEMA SQL command is not supported.
- NUMERIC data type is defined as zoned decimal on DB2 for iSeries and
packed decimal on other platforms.
- The FLOAT data type does not use the same storage. For portability
across platforms, do not use FLOAT(n).
- Not all features of the CREATE FUNCTION statement are supported
on each platform (see documentation).
- iSeries prior to V5R1
requires the statement to be processed by a special schema processor.
iSeries as of V5R1 would
require this only if the statement includes other DDL statements.
- OS/400 supports “SET
DEFAULT” clause ON DELETE.
- OS/400 supports DROP
statement with CASCADE behavior.
- Syntaxes of CREATE, ALTER and RENAME TABLE are different on the
two systems.