Help required urgently in formulating a sql query

Question

I need to formulate a query the detials of which are as follows
I have a table with columns
cid,st_dt,end_dt,yob,status
the data could be like
1,25-dec-99,31-dec-99,1964,null
1,01-jan-00,null,1963,null
1,27-dec-99,31-jan-00,null,a
1,04-feb-00,null,null,b
In a row in this table either yob or status
is null there can't be values for both in a single row.
Now i need an output for the above like
1,25-dec-99,27-dec-99,1964,null
1,28-dec-99,31-dec-99,1964,a
1,01-jan-00,31-jan-00,1963,a
1,01-feb-00,03-feb-00,1963,null
1,04-feb-00,null,1963,b
here as in the base table the end dt for
any row is null then it would have all the
attributes from that start dt onwards.
Can anybody help me out please. I need one sql script to get this output.
Thanks in advance.
null

Answer 1

Hey,
Here I have assumed that the table3 has a column named effdt and if it is then,
Select t1.deptid,t2.report2dept,t2.parent_org
from table1 t1, table2 t2 , table3 t3
where t1.deptid = t2.deptid
and t2.deptid = t3.deptid
and t3.effdt = (select max(effdt) from table3 where employeeid = t3.employeeid group by employeeid);
This may help you.
Regards,
Nilesh Goswami.