Try:

with CTE_In as

(

select

Employee,

[Function],

[DateTime],

ROW_NUMBER() OVER(PARTITION BY Employee, [Function] ORDER BY [DateTime]) as RN

from MyTable

where

[Function] in (1, 3)

)

select

i.Employee,

i.[Function] / 2 + 1 as [Type],

i.[DateTime] as DateTimeIn,

(select top 1 o.[DateTime]

from MyTable as o

where

o.Employee = i.Employee and

o.[Function] = i.[Function] + 1 and

o.[DateTime] > i.[DateTime] and

(o.[DateTime] < ni.[DateTime] or ni.[DateTime] is null)

order by

o.[DateTime]) as DateTimeOut

from CTE_In as i

left join CTE_In as ni

on ni.Employee = i.Employee and

ni.[Function] = i.[Function] and

ni.RN = i.RN + 1

Hope this helps.