SQL JOIN with multiple date condition - sql

Question

We have the first valuetable table and the query should check if there is
a next younger datetime in the correctiontable table and should add the corrvalue with the corrdatetime.
My problem query:
SELECT * FROM valuetable vt
LEFT JOIN correctiontable corr ON corr.value_id = vt.id WHERE vt.datetime <= corr.corrdatetime
is just delivering the last corrdatetime...
To clarify te results:
Row1 id1 should be NULL as the valuetable datetime is younger than the correction datetime
Row2 id2 should be 01/08/2017 00:00:00 as the datetime in valuetable is older but younger than the 01/12/2017 10:00:00 corrdatetime
Row3 id2 got its correction on 01/12/2017 10:00:00
Row4 id3 is NULL, there is no corrdatetime in correctiontable for it
Thank you all ++
+----------------------------------+
| valuetable |
+----------------------------------+
| id | datetime | value |
+----+---------------------+-------+
| 1 | 22/07/2017 13:00:00 | 123 |
+----+---------------------+-------+
| 2 | 10/08/2017 09:00:00 | 456 |
+----+---------------------+-------+
| 2 | 05/12/2017 20:00:00 | 789 |
+----+---------------------+-------+
| 3 | 11/11/2017 11:11:11 | 012 |
+----+---------------------+-------+
+-------------------------------------------------+
| correctiontable |
+-------------------------------------------------+
| id | value_id | corrdatetime | corrvalue |
+----+----------+---------------------+-----------+
| 1 | 2 | 01/08/2017 00:00:00 | 888 |
+----+----------+---------------------+-----------+
| 2 | 2 | 01/12/2017 10:00:00 | 999 |
+----+----------+---------------------+-----------+
| 3 | 1 | 01/08/2017 20:00:00 | 111 |
+----+----------+---------------------+-----------+
+--------------------------------------------------------------------+
| Result (as it should be) |
+--------------------------------------------------------------------+
| id | datetime | corrdatetime | value | corrvalue |
+----+---------------------+---------------------+-------+-----------+
| 1 | 22/07/2017 13:00:00 | NULL | 123 | NULL |
+----+---------------------+---------------------+-------+-----------+
| 2 | 10/08/2017 09:00:00 | 01/08/2017 00:00:00 | 456 | 888 |
+----+---------------------+---------------------+-------+-----------+
| 2 | 05/12/2017 20:00:00 | 01/12/2017 10:00:00 | 789 | 999 |
+----+---------------------+---------------------+-------+-----------+
| 3 | 11/11/2017 11:11:11 | NULL | 012 | NULL |
+----+---------------------+---------------------+-------+-----------+

Answer 1

Assuming "younger" means "logically less than", this should work for you.
select *
from valuetable a
outer apply (
select top 1 *
from correctiontable y
where y.value_id = a.id
and y.datetime < a.datetime
order by y.datetime desc
) b

Answer 2

Many Thanks to #KindaTechy for delivering me the right path!
I've created two querys, one for MySQL and one for >= Oracle 12.1
For MySQL:
SELECT *
FROM valuetable vt
LEFT JOIN correctiontable ON correctiontable.id
=
(SELECT corr.id
FROM correctiontable corr
WHERE vt.id = corr.value_id
AND vt.datetime <= corr.corrdatetime
ORDER BY datetime DESC
LIMIT 1)
For Oracle:
select *
from valuetable vt
outer apply (
select *
from correctiontable corr
where corr.value_id = vt.id
and corr.corrdatetime < vt.datetime
order by corr.corrdatetime desc
FETCH FIRST 1 ROWS ONLY
) b;

Answer 3

I found a working query, but your id column of valuetable should be unique, because otherwise you get a cross product.
SELECT vt.id, vt.datetime, corr.corrdatetime, vt.value, corr.corrvalue
FROM valuetable vt
LEFT JOIN correctiontable corr
ON corr.value_id = vt.id
AND vt.datetime >= corr.corrdatetime
By changing the date constraint from WHERE-CLAUSE to ON-CLAUSE it will impact only the join and not the result.
A made a sample for you http://sqlfiddle.com/#!9/301a6/4/0
When you need that non-unique id, the query must be improved. And also the test data set.