update A
set A.first_name = B.first_name,A.last_name = B.last_name
from dbo.tblA as A inner join dbo.tblB as B
on A.emp_id = B.emp_id
----
UPDATE A
SET A.<column_name> = B.<column_name>, ...
FROM <table_name> A
[ INNER | LEFT ] JOIN <table_name1> B ON <join_predicate>
[ WHERE Condition(s) ]