Update entire table with sequence number in oracle - sql

Question

I want to update table with sequence number, I cant create procedure or sequence object so need a update query for this. I have a table with date column, based on minimum date I need to generate a number.
Table Data:-
Date_Value
----------
5th Feb 11
2nd Jan 11
11th Jan 11
After Update :-
SrNo Date_Value
-------------------
1 2nd Jan 11
2 11th Jan 11
3 5th Feb 11

Answer 1

merge into foo
using
(
select rowid as rid,
row_number() over (order by date_value) as seqno
from foo
) t on (foo.rowid = t.rid)
when matched then update
set srno = t.seqno;
SQLFiddle demo: http://sqlfiddle.com/#!4/d8cc5/2

Answer 2

Your example shows that you store dates as a string using custom representation - not compliant with dates format. So we need to convert your dates to date datatype to be able to order them accordingly.
SQL> create table TB_DATES
2 (
3 DATE_VALUE VARCHAR2(11)
4 )
5 /
Table created
SQL>
SQL> insert into tb_dates(date_value)
2 select '5th Feb 11' from dual union all
3 select '2nd Jan 11' from dual union all
4 select '6th Feb 11' from dual union all
5 select '11th Jan 11' from dual
6 ;
4 rows inserted
SQL> commit;
Commit complete
SQL> select * from tb_dates;
DATE_VALUE
-----------
5th Feb 11
2nd Jan 11
6th Feb 11
11th Jan 11
SQL> alter table tb_dates add srno number;
Table altered
QL> select * from tb_dates;
DATE_VALUE SRNO
----------- ----------
5th Feb 11 null
2nd Jan 11 null
6th Feb 11 null
11th Jan 11 null
SQL> merge into tb_dates t
2 using(
3 select rownum rn
4 , Date_value
5 , rid
6 from ( select to_date(concat(lpad(dy, 2, '0'), tr), 'dd Mon yy') dt
7 , Date_value
8 , rid
9 from (select regexp_substr(substr(Date_value, 1, regexp_instr(date_value, '[[:space:]]') - 1), '[[:digit:]]+') dy
10 , substr(Date_value, regexp_instr(date_value, '[[:space:]]'), length(Date_value)) tr
11 , Date_value
12 , rowid rid
13 from tb_dates)
14 order by 1
15 ) ) q
16 on (q.rid = t.rowid)
17 when matched
18 then update set t.srno = q.rn
19 ;
Done
SQL> commit;
Commit complete
select * from tb_dates;
DATE_VALUE SRNO
----------- ----------
5th Feb 11 3
2nd Jan 11 1
6th Feb 11 4
11th Jan 11 2
SQL> select * from tb_dates order by srno;
DATE_VALUE SRNO
----------- ----------
2nd Jan 11 1
11th Jan 11 2
5th Feb 11 3
6th Feb 11 4