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select department_id,TO_NUMBER(null) location, hire_date from employees union select department_id, location_id, TO_DATE(null) hired from departments In this example, the name location is given as the dummy column heading. The TO_NUMBER function is used in the first query to match the NUMBER data type of the LOCATION_ID column retrieved by the second query. Similary, the TO_DATE function in the ..

select department_id,TO_NUMBER(null) location, hire_date from employees union select department_id, location_id, TO_DATE(null) hired from departments In this example, the name location is given as the dummy column heading. The TO_NUMBER function is used in the first query to match the NUMBER data type of the LOCATION_ID column retrieved by the second query. Similary, the TO_DATE function in the ..

SELECT employee_id, department_id FROM employee_id WHERE (employee_id, department_id) IN(SELECT employee_id, department_id FROM employees {UNION|UNION ALL|INTERSECT|MINUS} SELECT employee_id, department_id FROM job_history);

SELECT employee_id, department_id FROM employee_id WHERE (employee_id, department_id) IN(SELECT employee_id, department_id FROM employees {UNION|UNION ALL|INTERSECT|MINUS} SELECT employee_id, department_id FROM job_history);

select employee_id,last_name,job_id,salary from employees where salary ANY : check minimum value = ANY : IN or "or" > ALL : check the maximum value < ALL : check the Minimum value

select employee_id,last_name,job_id,salary from employees where salary ANY : check minimum value = ANY : IN or "or" > ALL : check the maximum value < ALL : check the Minimum value

Enclose subqueries in parantheses.Place subqueries on the right side of the comparison condition.The ORDER BY clause in the subquery is not needed unless you re performing TOP-N analysis.Using single-row operators with single-row subqueries, and use multiple-row operators with multiple-row subqueries.

Enclose subqueries in parantheses.Place subqueries on the right side of the comparison condition.The ORDER BY clause in the subquery is not needed unless you re performing TOP-N analysis.Using single-row operators with single-row subqueries, and use multiple-row operators with multiple-row subqueries.

SELECT select_list FROM table WHERE expr operator (SELECT select_list FROM table);The subquery(inner query) executes once before the main query(outer query).The result of the subquery is used by the main query. You can place the subquery in a number of SQL clauses, including the following:WHERE clauseHAVING clauseFROM clause

SELECT select_list FROM table WHERE expr operator (SELECT select_list FROM table);The subquery(inner query) executes once before the main query(outer query).The result of the subquery is used by the main query. You can place the subquery in a number of SQL clauses, including the following:WHERE clauseHAVING clauseFROM clause