Outer joins

Use standard ISO outer join syntax instead of the old IBM® Informix® OUTER() syntax.

Old IBM Informix SQL outer joins specified with the OUTER keyword in the FROM part are not standard:
SELECT * FROM master, OUTER ( detail )
  WHERE master.mid = detail.mid
    AND master.cdate IS NOT NULL
Table 1. Database server support of OUTER JOIN syntax
Database Server Type Supports IBM Informix OUTER join syntax
IBM DB2® UDB No (but translated by driver)
IBM Informix (1) Yes
Microsoft™ SQL Server (2) No (but translated by driver)
MySQL No (but translated by driver)
Oracle Database Server No (but translated by driver)
PostgreSQL No (but translated by driver)
Sybase ASE No (but translated by driver)
SQLite No (but translated by driver)
Most recent database servers now support the standard ANSI outer join specification:
SELECT * FROM master LEFT OUTER JOIN detail ON (master.mid = detail.mid)
  WHERE master.cdate IS NOT NULL

You should use recent database servers and use ANSI outer joins only.