Are you using Peoplesoft's Query Manager web interface to create your query? If yes, there's a little trick to getting the outer joins to work....
If your using Query Manager to write the query, doing the outer joins involves using an expression to create the join. Peoplesoft Query Manager creates inner joins by default between two tables, which you can see in the Criteria tab fields in the Query Manager.
For example, if your hit edit criteria for an inner join on the key fields APPLID in Tables A and D, you would see A.APPLID in "Expression 1" under the criteria field and would be equal to D.APPLID in "Expression 2".
But, if you needed an outer join between those to fields,
you would edit the inner join by changing expression 1 to A.APPLID *=D.APPLID AND 1. The *= creates the inner join and is specific to MS SQL Server. Oracle uses a different syntax. In expression 2 you need to change the expression type from "field" to "constant" and enter a 1 in the define constant field.
This should allow the outer join to work.