MySQL - SELECT columns according to their values - php

Question

I have an events table in my database, and each event can
have up to 5 different dates.
Date1 in the table is always before date2, date2 before date3 etc.
Given 2 dates in the search form, I'm trying to find the events between them.
My table is designed as follows:
id | name | date1 | date2 | date3 | date4 | date5
1 | test1 | 2013-05-24| 2013-05-25 | 0000-00-00| 0000-00-00| 0000-00-00
2 | test2 | 2013-06-01| 2013-06-08 | 2013-06-15| 2013-06-23| 2013-06-30
3 | test3 | 2013-03-15| 0000-00-00 | 0000-00-00| 0000-00-00| 0000-00-00
$datefrom , $dateto are the two variables from the search form.
Now the $datefrom for example, will always search in date1 of the table.
But $dateto has to search in date5, and if it is null to date4 and so on.
The best query I came up with so far is this:
SELECT * FROM events
WHERE
IF(date1 != '0000-00-00', IF(date1>='2012-12-19', 1, 0),0) = 1
AND CASE
WHEN date5!='0000-00-00' THEN IF(date5<='2012-12-31', 1, 0)
WHEN date4!='0000-00-00' THEN IF(date4<='2012-12-31', 1, 0)
WHEN date3!='0000-00-00' THEN IF(date3<='2012-12-31', 1, 0)
WHEN date2!='0000-00-00' THEN IF(date2<='2012-12-31', 1, 0)
END
But it is not working very well, for example this query returns rows with its oldest date being in 2013. I don't know if CASE is the right approach to begin with.
Any ideas?? Thanks for your time!

Answer 1

you can use it so simple with GREATEST
SELECT name , date1 date_start, GREATEST(date2,date3,date4,date5) date_end
FROM events
and will output like that
NAME DATE_START DATE_END
jack 2013-05-24 2013-05-25
peter 2013-06-01 2013-06-30
here THE DEMO SQLFIDDLE

Answer 2

Try this:
SELECT
id,
name
FROM
(
SELECT
id,
name,
MIN(EventDate) AS "FromDate",
MAX(EventDate) AS "ToDate"
FROM
(
SELECT id, name, date1 As "EventDate" FROM events
UNION ALL
SELECT id, name, date2 FROM events
UNION ALL
SELECT id, name, date3 FROM events
UNION ALL
SELECT id, name, date4 FROM events
UNION ALL
SELECT id, name, date5 FROM events
) t
GROUP BY id, name
) t
WHERE FromDate > #fromdate
AND ToDate < #todate;
SQL Fiddle Demo
However, if you want to get the data in the same way as it is in the events table, you can do this:
SELECT
e.*
FROM
(
SELECT
id,
name,
MIN(EventDate) AS "FromDate",
MAX(EventDate) AS "ToDate"
FROM
(
SELECT id, name, date1 As "EventDate" FROM events
UNION ALL
SELECT id, name, date2 FROM events
UNION ALL
SELECT id, name, date3 FROM events
UNION ALL
SELECT id, name, date4 FROM events
UNION ALL
SELECT id, name, date5 FROM events
) t
GROUP BY id, name
) t
INNER JOIN events e ON t.id = e.id
WHERE t.FromDate > #fromdate
AND t.ToDate < #todate;
For instance, for #fromdate = '2012-05-01' and #todate = '2012-06-15', this will give you:
| ID | NAME | DATE1 | DATE2 | DATE3 | DATE4 | DATE5 |
---------------------------------------------------------------------------------------------------
| 1 | test1 | May, 24 2013 00:00:00+0000 | May, 25 2013 00:00:00+0000 | (null) | (null) | (null) |