Union
select T.employee_id \n from\n (select * from Employees\n union \n select * from Salaries) as T\n group by T.employee_id \n having count(employee_id)<2\n order 
select T.employee_id \n from\n (select * from Employees\n union \n select * from Salaries) as T\n group by T.employee_id \n having count(employee_id)<2\n order by employee_id asc\n
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