Here is your sample data and some code. You tell us what the problem is:

CREATE TABLE abc

(gg_key int,

fg_sta_key int,

fg_eff_dt_key int,

fg_end_dt_key int,

fg_seq_nbr int)

insert into abc values(19925,2,20130128,20130128,1)

insert into abc values (19925,8,20130128,20130128,2)

insert into abc values(19925,1,20130129,20130416,3)

insert into abc values (19925,5,20130417,NULL,4);

select

gg_key,

fg_sta_key,

fg_eff_dt_key,

fg_end_dt_key,

fg_seq_nbr,

cast(cast(fg_eff_dt_key as varchar) as date) as fg_eff_dt,

case when fg_end_dt_key is null then getdate() else cast(cast(fg_eff_dt_key as varchar) as date) end as fg_end_dt,

datediff(day,cast(cast(fg_eff_dt_key as varchar) as date),case when fg_end_dt_key is null then getdate() else cast(cast(fg_eff_dt_key as varchar) as date) end) DayDiff

from abc;

drop table abc;

Questions:

1) Why all the "key" fields (fg_sta_key, fg_eff_dt_key, fg_end_dt_key)

2) Why are date values being stored as integers, these should be stored using date or date/time data types.