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take min value from the table.

Posted on 2014-02-05
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Last Modified: 2014-02-16
for eg. I have a table with name EXAMPLE with four columns col1,col2,col3,col4

I have a query like below


select col1,col2,col3,col4 from example
where (condition 1)
and   (condition 2)
and (condition 3)

After executing the query I am having the below results.

col1               col2      col3     col4
------              -------     -------    -------
23                    34          56       89
45                    56          65       85
11                    32          11       63

In this result,
I need only one row, that is take the minimum value for col2 from the results and get the corresponding col1 value .

What is the simplest way to achieve this.?
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Question by:sakthikumar
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5 Comments
 
LVL 25

Accepted Solution

by:
chaau earned 250 total points
ID: 39837876
I think this is the simplest one:
SELECT *
  FROM (SELECT col1,col2,col3,col4 from example
  where (condition 1)
     and   (condition 2)
     and (condition 3)
  ORDER BY col2)
 WHERE ROWNUM = 1;

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0
 
LVL 37

Assisted Solution

by:Geert Gruwez
Geert Gruwez earned 250 total points
ID: 39838105
with x as (
  select col1,col2,col3,col4 from example
  where (condition 1)
  and   (condition 2)
  and (condition 3))
select * from x
where col2 = (select min(col2) from x);
0
 
LVL 8

Expert Comment

by:Surrano
ID: 39838197
An addition the comments above: there is a difference if col2 is not unique.
- chaau will return exactly one row where col2 is minimum. Which one of several records with same col2 value is undefined.
- Geert will return all the rows where col2 is minimum

Performance-wise, I feel Geert's solution faster (should matter only if we are talking about millions of rows) but if you need exactly one row you can still add the rownum clause. My habit is to use "rownum<2" instead of "rownum=1" but I don't think there's a difference in Oracle planning.
0
 
LVL 37

Expert Comment

by:Geert Gruwez
ID: 39838743
> Performance-wise, I feel Geert's solution faster

it might even be faster if you add the /*+ MATERIALIZE */ hint
depends on size ... again

with x as (
  select /*+ MATERIALIZE */ col1,col2,col3,col4 from example
  where (condition 1)
  and   (condition 2)
  and (condition 3))
select * from x
where col2 = (select min(col2) from x);
0
 
LVL 32

Expert Comment

by:awking00
ID: 39839454
>>I need only one row, that is take the minimum value for col2 from the results and get the corresponding col1 value .<<
So from your example, you would just want to return 11 (i.e. the value of col1 where col2 is at its minimum)?
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