SQL compatibilities

Unlike other database technologies, Db2 can run applications developed in other database technologies with minimal changes.

The Db2 registry variable DB2_COMPAT_VECTOR is used to active this compatibility. Compatibility can be set at different levels. For example, to set compatibility for Oracle, use the db2set command as follows:

    db2set DB2_COMPAT_VECTOR=ORA
    db2stop
    db2start

The following is the list of other databases that are supported under DB2_COMPAT_VECTOR:

• Oracle (ORA)
• Sybase (SYB)
• MySQL (MYS)

Some compatibility features are always active. For example, DISTINCT can be replaced with UNIQUE, and MINUS can replace EXCEPT. Most of the features that are automatically active provide an application portability bridge between Db2 and PostgreSQL or Netezza.