Select-Options in AMDP

Hi Folks,

I am developing a ABAP report using AMDP and we have 7.4 SP 09.

We have select-options and parameters in selection screen. 

I am facing below problem,

1.  I have declared AMDP importing parameter type string for date where condition and it is not working but when I am giving importing parameter type char8 then it working.

e.g.

          CLASS-METHODS : GET_DATA

                                            IMPORTING VALUE(IP_WHERE_FK) TYPE string

                                            EXPORTING VALUE(EX_FINAL) TYPE GT_FINAL.

2. When I am trying to deal with  select-option, getting lost.

Tried  #APPLY_FILTER ( But might cause performance issue) even though its not throwing result set.

e.g. it_tab = select * from XYZ;

      ex_final =  APPLY_FILTER(:IT_TAB, : (Dynamic where condition));

I hope will get my doubt cleared.

Regards,

Amol