Join tables displaying one column based on max of another - sql

Question

I'm joining some tables and need to return values based upon a max value without actually returning the max value column itself.
Table1
+------------+----------+---------+
| EmployeeID | TaskTime | JobType |
+------------+----------+---------+
| 1000 | 5:14:00 | Read |
| 1000 | 5:42:00 | Write |
| 1000 | 6:14:00 | Write |
+------------+----------+---------+
Table2
+------------+-----------+-----------+---------+
| EmployeeID | ClockType | JobDetail | JobType |
+------------+-----------+-----------+---------+
| 1000 | 5:03:00 | This | Read |
| 1000 | 5:21:00 | That | Write |
+------------+-----------+-----------+---------+
What I want to now return is the JobDetail corresponding to the last ClockType before the TaskTime. So something like this:
+------------+----------+---------+-----------+
| EmployeeID | TaskTime | JobType | JobDetail |
+------------+----------+---------+-----------+
| 1000 | 5:14:00 | Read | This |
| 1000 | 5:42:00 | Write | That |
| 1000 | 6:14:00 | Write | That |
+------------+----------+---------+-----------+
My query I'm using is as follows:
SELECT DISTINCT X.*, t2.JobDetail
FROM
(
SELECT t1.EmployeeID, t1.TaskTime, t1.JobType
FROM Table1 t1
WHERE t1.EmployeeID=10000
) X
LEFT JOIN Table2 t2 on (X.EmployeeID = t2.EmployeeID) and (X.JobType = t2.JobType) and (t2.ClockTime < X.TaskTime)
This returns all rows where ClockTime < TaskTime, as expected. I just cant seem to figure out how to show only the last ClockTime before TaskTime. I tried changing my JOIN like the following but it returns all null values for JobDetail:
LEFT JOIN
(
SELECT row_number() over(partition by ClockTime order by ClockTime desc) rn, JobDetail, ClockTime as time2
FROM Table2) t2
on (X.EmployeeID = t2.EmployeeID) and (X.JobType = t2.JobType) and (t2.ClockTime < X.TaskTime)

Answer 1

You can try using TOP and Apply to get the max values.
select *
from Table1 as t1
cross apply ( select top 1
JobDetail
from Table2 as t2
where t1.EmployeeID = t2.EmployeeID
and t1.JobType = t2.JobType
and t1.TaskTime >= t2.ClockType
order by ClockType desc) as jt
SQL Fiddle
Using Row_Number()
select *
from ( select t1.EmployeeID
, t1.TaskTime
, t1.JobType
, t2.JobDetail
, row_number() over (partition by t1.EmployeeID, t1.JobType, t1.TaskTime
order by t2.ClockType desc) as Rn
from Table1 as t1
join Table2 as t2 on t1.EmployeeID = t2.EmployeeID
and t1.JobType = t2.JobType
and t1.TaskTime >= t2.ClockType) as t
where Rn = 1
SQL Fiddle