qazmlp1209_at_rediffmail.com wrote:
> For the given problem, we have arrived at 2 solutions:
>
> Solution-1:
>>> update tab2 t2_alias
>>> set col_c_2 = null
>>> where exists
>>> (select col_a_1
>>> from
>>> (select col_a_1, col_b_2, col_C_2, count(col_a_1) over (partition by
>>> col_a_1
>>> order by col_a_1) as data_count
>>> from tab1
>>> join tab2 on (col_a_1 = col_a_2)
>>> where col_b_1 = 'true'
>>> )
>>> where data_count = 1
>>> and col_a_1 = t2_alias.col_a_2)
>
> Solution-2:
>> UPDATE tab2
>> SET col_c_2 = null
>> WHERE col_a_1 IN
>> ( SELECT col_a_1 FROM tab1 WHERE col_b_1 = 'true'
>> INTERSECT
>> SELECT col_a_2 FROM tab2 GROUP BY col_a_1 HAVING count(1) = 1
>> );
>
> Can anybody comment on which one is more performant ...
No. Is there something preventing you from running them?
--
Daniel A. Morgan
University of Washington
damorgan_at_x.washington.edu
(replace x with u to respond)
Puget Sound Oracle Users Group
www.psoug.org
Received on Mon Jan 29 2007 - 13:19:15 CST
