Get the later of the 4 dates.

Question

Hope I can get help, I am green to this but I wish to learn for my reports.
I have 4 dates column.
Date1
Date2
Date3
Date4
From table_date
I need get the later of the 4 dates.
I understand there is a greatest function
But I don’t know if this is what you need.
Also
Do I need to do any conversion as far as date goes?
it could ne any of the date fields for each record.
i wish for the output to be AS current_date Field
Thanks.

Answer 1

Hi,
Do you want to know what column date is greatest ?
So, try :
  1* create table tbl8(date1 date, date2 date, date3 date, date4 date)
SQL> /
Table created.
SQL> insert into tbl8 values (sysdate,sysdate+1,sysdate+2,sysdate+4);
1 row created.
SQL> ed
Wrote file afiedt.buf
  1* insert into tbl8 values (sysdate+5,sysdate+10,sysdate+9,sysdate-5)
SQL> /
1 row created.
SQL> ed
Wrote file afiedt.buf
  1  select col_name, dt
  2  from
  3  (select 'date1' col_name, date1 as dt from tbl8 union all
  4   select 'date2' col_name, date2 as dt from tbl8 union all
  5   select 'date3' col_name, date3 as dt from tbl8 union all
  6   select 'date4' col_name, date4 as dt from tbl8
  7   order by dt desc)
  8* where rownum=1
SQL> /
COL_N DT
date2 01/05/06
SQL> Nicolas.