Select min value with specific where filters MYSQL

Question

I have a little trouble with my subquery. I try to only take the nearest event in a table with a min value, but I need it to be confirmed (confirmed = 1 and cancelled = 0)

There's my table :

uid | location | date         | open    | close  | confirmed | 
1   |  aaa     |  2015-05-11  |  12:00  |  14:30 |  1        |
2   |  aaa     |  2015-05-12  |  15:00  |  22:30 |  0        |
3   |  aaa     |  2015-05-15  |  11:00  |  18:30 |  0        |
4   |  aaa     |  2015-05-16  |  09:00  |  16:00 |  1        |

And there is my query : ( $now is a php date of current hour (H:i) and $today a php date in format Ymd)

SELECT location, MIN(date)
FROM  table
WHERE confirmed = 1
AND IF (
    (close > '$now' AND date = '$today') OR (date> '$today'), 1, 0
)
GROUP By location

So in the test format, we are May 11 at 17:00. The first one shouldn't be selected because it happened in the past (this morning) and the second one should not be selected too because i put confirmed to 0

The expected result is

aaa  | 2015-05-16

because its the nearest with the confirm to true,

but it always returns me

aaa  | 2015-05-12

It doesn't care about the where statement of confirmed = 1, but it cares about the if (close > '$now' AND date = '$today') OR (date> '$today'), 1, 0 because it returns me the second one.

Can someone provide me some help please?

PS: It's all in MySQL

Thank you.

-- Carlos

EDIT :::

I just tried to add some value in the select (SELECT *, MIN(date))

and it returns me asymetric data ???

I got

| 4  | aaa  | 2015-05-16 | 09:00 | 16:00 | 1 | 2015-05-12

So the first date is the good one and the second one (with the min()) isn't the good one.

LAST EDIT :::

AS suggested spencer7593 (thanks to him/her), i just removed the min(date) and it automatically returns me the data I want, the good sql is :

SELECT *
FROM  table
WHERE confirmed = 1
AND IF (
    (close > '$now' AND date = '$today') OR (date> '$today'), 1, 0
)
GROUP By location

Answer 1

Try like this:

SELECT location, MIN(date)
FROM  table
WHERE confirmed = 1
AND ((close > '$now' AND date = '$today') OR (date> '$today'))
GROUP By location

Maybe the If statement is making the behavior wrong.

Answer 2

Given the example data, it certainly doesn't look like the date value of 2015-05-12 should be returned.

I'm questioning what the datatypes of the columns are, the confirmed column in particular. If that column is CHAR or VARCHAR , perhaps the comparison is being done as character, rather than numeric, and there's some hidden characters that's making it unequal.

If that's the case, and it's trailing characters in the column value, you can try casting confirmed to numeric by adding a zero to it in the statement, eg

WHERE confirmed+0 = 1

That expression confirmed+0 will be evaluated in numeric context.

I'm also suspicious of the datatypes of the date and close columns, if those are also VARCHAR or CHAR... though that wouldn't explain why the predicate on confirmed is being ignored.

We're just guessing, there's not enough information to really tell what's happening.

For debugging this type of issue, echo or vardump the SQL text before it's sent to the database, so you can see what's actually being sent.

  $sql = "SELECT ....   " . $var . " ... ORDER BY 1";
  echo $sql;  # for debugging

  $dbh->query($sql);

I'd take that SQL text thats emitted, and test in another client. I'd try removing the MIN aggregate function and the GROUP BY , and return all of the relevant columns from the rows, to see the actual rows that are being grouped.

Answer 3

Assuming you are trying to find the location from the first confirmed record after the supplied date and time.

SELECT `location`, `date`
FROM `table`
WHERE `confirmed` = 1 
   AND (`date` > '$today'
         OR (`date` = '$today' AND `close` > '$now')
       )
ORDER BY `date`, `close`
LIMIT 1
;