CREATE VIEW employee_view AS
SELECT t1.* FROM
(SELECT * FROM employee
UNION ALL
SELECT * FROM employee_extnl) t1
JOIN
(SELECT employeeid, max(record_datetime) max_modified FROM
(SELECT * FROM employee
UNION ALL
SELECT * FROM employee_extnl) t2
GROUP BY employeeid) s
ON t1.employeeid = s.employeeid AND t1.record_datetime = s.max_modified;