Query to find GL periods for a given legal entity

Query to find GL periods for a given legal entity:

 select gp.period_name
                  from gl_ledger_norm_seg_vals bsv,gl_ledgers gl, gl_periods gp
                 where  1=1
                 AND Bsv.Legal_Entity_Id = :Legal Entity Id
                 And Bsv.Segment_Type_Code = 'B'
                AND sysdate between nvl(bsv.start_date,sysdate-1) and nvl(bsv.end_date,sysdate+1)
                And Gl.Object_Type_Code = 'L'                
                And Gl.Ledger_Category_Code = 'PRIMARY'
                And Gl.Ledger_Id=Bsv.Ledger_Id
                AND gp.period_set_name=gl.period_set_name
                order by gp.start_date
                ;

Derive GL Start and End Dates..

select start_date,end_date
                  from gl_ledger_norm_seg_vals bsv,gl_ledgers gl, gl_periods gp
                 where  1=1
                 AND Bsv.Legal_Entity_Id = :p_Legal_entity_id
                 And Bsv.Segment_Type_Code = 'B'
                AND sysdate between nvl(bsv.start_date,sysdate-1) and nvl(bsv.end_date,sysdate+1)
                And Gl.Object_Type_Code = 'L'                
                And Gl.Ledger_Category_Code = 'PRIMARY'
                And Gl.Ledger_Id=Bsv.Ledger_Id
                AND gp.period_set_name=gl.period_set_name
                and gp.period_name = :p_period_name
                order by gp.start_date

                ;