SQL Server 2012 :: Update A Column Using Value Of Another Column

I have a student table like this studentid, schoolID, previousschoolid, gradelevel.

I would like to load this table every day from student system.

During the year, the student could change schoolid, whenever there is a change, I would put current records schoolid to the previous schoolid column, and set the schoolid as the newschoolid from student system.

My question in my merge statement something like below

Merge into student st
using (select * from InputStudent ins)
on st.id=ins.studentid

When matched then update

set st.schoolid=ins.schoolid
, st.previouschoolid= case when (st.schoolid<>ins.schoolid) then st.schoolid
else st.previouschoolid
end
, st.grade_level=ins.grade_level
;

My question is since schoolid is et at the first line of set statement, will the second line still catch what is the previous schoolid?