Know lower value and its column name from select - php

Question

I have a PHP document with MySQL database storing with the following structure:
DATE FIELD
24 float values corresponding to the 24 hours. (The name is 1h, 2h, 3h, 4h... 24h)
I fetch a row with the simple select: SELECT * from table where DATE = "2014-02-02" obtaining the 25 fields.
I want to know wich field of 1h, 2h, 3h.... has the lower value. I'm trying doing that with PHP and min() function, but I only retreive the value, not the index of the array.
Is this possible a simple way to know this result? Maybe in the SQL function?
Thank you
EDIT: I tried this (Considering $arraySQL has a valid result obtained before):
function ObtainArrayFromSQL($arraySQL){
$array = array();
for ($i = 1; $i < 25; $i++)
{
array_push($array, $data_day[$i."h"]);
}
return $array;
}
[...]
$array = ObtainArrayFromSQL($arraySQL)
echo min($array);

Answer 1

Assuming you are using MySQL, you can use the least() function:
select t.*,
(case when col1 = leastval then 'col1'
when col2 = leastval then 'col2'
when col3 = leastval then 'col3'
. . .
when col24 = leastval then 'col24'
end) as leastvalcol
from (select t.*,
least(col1, col2, . . . , col24) as leastval
from table t
) t;
Before complaining about all the typing you need, you should know that this query is much more complicated than it needs to be -- because you are storing things on a row that should be in a column. Your table should have a separate row for each hourly value, rather than putting all the daily values on one row. With a more normalized structure, your query would be much simpler.
EDIT:
This table would have columns such as:
Date date,
Hour time, -- or int or varchar() depending on how you really want it captured
Value float
Then the query might look like:
select date, min(value) as minvalue,
substring_index(group_concat(hour order by value asc), ',', 1) as minhour
from newtable t
group by date;

Answer 2

At first, thank you everyone for the help.
Finally I made the solution with PHP instead of manipulate a big SQL sentence.
I create the array using the function ObtainArrayFromSQL, and then, use the function array_search() with min() as needle in the haystack (array).
function ObtainArrayFromSQL($arraySQL){
$array = array();
for ($i = 1; $i < 25; $i++)
{
array_push($array, $data_day[$i."h"]);
}
return $array;
}
...
$index_lower_value = array_search(min($array), $array);
Thank you everyone!