Differences Between DB2 UNIX & DB2 OS/400

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.