how can we apply query on column combined with two columns
i use it
SELECT CONCAT(emp_fname,' ',emp_lname) AS emp_name
FROM employee_personal
where emp_name NOT IN (select emp_name from task_allocation where proj_name='abc')
A column alias definied in the SELECT clause of the query can be only used in the ORDER BY clause of this query,
it cannot be used in any other clauses.
This should work: