Effective Date, Sequence Effective in the script

[#1]

Good morning, this is my first post on the forum I hope to be posting in the right area.

I'm learning to work with QlikView but caught at one point and I hope you can help me.

I have two tables:

tab_mov_acad - With has the status of my students for effective date, effective sequence.

tab_mov_acad_detalhes_desnormalizada - This table'm desnormalizando day by day my records as a basis for analysis.

Issue:

For me to find out what the status of my student in a "date" (column) in the database I use the code:

select a.acao,

          a.motivo,

          b.data

  from tab_mov_acad a,

         tab_mov_acad_detalhes_desnormalizada b

  and a.data_efetiva = ( select max(c.effdt)

                                    from tab_mov_acad c

                                  where c.data_efetiva <= b.data

                                      and a.cod_pessoa = c.cod_pessoa

                                      and a.nivel_ensino = c.nivel_ensino

                                      and a.stdnt_car_nbr = c.stdnt_car_nbr

                                      and a.programa = c.programa)

  and a.sequencia_efetiva = ( select max(e.data_efetiva)

                                              from tab_mov_acad e

                                            where b.data_efetiva  = e.data_efetiva

                                                and a.cod_pessoa    = e.cod_pessoa

                                                and a.nivel_ensino  = e.nivel_ensino

                                                and a.stdnt_car_nbr = e.stdnt_car_nbr

                                                and a.programa      = e.programa)   

Can help me?

grateful Victor