HELLO *.*

I´m writing an SQL instruction to work with SQL SERVER and ORACLE.

When I'm selecting the fields, I need to use the "CASE" option of the SQL SERVER, like this:

select Fieldx = CASE 
	           WHEN IT.UNIDADE=PRD.UNID1 THEN 1
                 WHEN IT.UNIDADE=PRD.UNID2 THEN PRD.FACONV
	         ELSE PRD.FACONV3
               END
 from ...

Using ORACLE the instruction is:

select Fieldx = (DECODE(IT.UNIDADE,
                        PRD.UNID1,1,
                        PRD.UNID2,PRD.FACONV
                        PRD.FACONV3 ))
from ...

I used DECODE to compare if the fields was equal, now the question:
How can I see (in ORACLE) if the field is >, >=, <. <> ?

This is the SQL SERVER instruction:

select fieldx = Case
       when p.IncIcms = 0 then 0 	
       when p.IncIcms <> 0 and t.UsoMens = 'A' then 200
       when p.IncIcms <> 0 and t.UsoMens <> 'A' and AliqICMS = 0 then ?Estados.AliqIcms
       when p.IncIcms <> 0 and t.UsoMens <> 'A' and AliqICMS <> 0 then AliqICMS
    end