Anything similar in Oracle to Microsoft's IIF function?

As we can not use condition in 'DECODE' function, unlike the 'IIF' function of Ms-ACCESS / SQL server. Is there any function or mechanism to use in the same manner as we do with the IIF function in SQL Server?

Case is is cited as follows:
Table Emp holds the employee wise scale and scale opt for. Depending on the status of the employee scale can be selecetd from scale table. Each Employee can have either of the following status as R - Regular & D - Deputationst, T - Trainee. In case of Deputationist, Scale_optfor option, which indicates eiher Parent scale (where scale_optor = 'P'i.e. Scale of Deputatinst) or Regular scale (where scale_optfor = 'R' i.e. scale for Regular employee), can be selected. Based on this selection we want to select the scale from scale table based on the following condition:

 if scale_optfor = 'P' then
   SELECT scale,basic FROM scale
   WHERE stat = emp.stat
 else
   SELECT scale,basic FROM scale
   WHERE stat = 'R'
 end if ;

Table 'Emp' contains:

 stat Varchar2(1) -values -  R,D,T
 emp_cd Varchar2(5),
 scale_optfor Varchar2(1) - values P,R
 scale  Number(3).

  scale  Number(3),
  Basic  Number(8,2),
  stat   Varchar2(1) - R, D, T .

 CASE WHEN condition THEN
expression1 ELSE expression2 END

SELECT
       CASE WHEN e.scale_optfor = 'P' THEN (SELECT scale FROM scale WHERE
stat = e.stat) END as Pscale,
       CASE WHEN e.scale_optfor = 'P' THEN (SELECT basic FROM scale WHERE
stat = e.stat) END as Pbasic,
       CASE WHEN e.scale_optfor <> 'P' THEN (SELECT scale FROM scale WHERE
stat = 'R') END as Rscale,
       CASE WHEN e.scale_optfor <> 'P' THEN (SELECT basic FROM scale WHERE
stat = 'R') END as Rbasic
  FROM emp e;