Oracle-4: Subqueries

Note on subqueries:

    1) Subqueries must be enclosed in parentheses;

    2) The subquery should be placed on the right side of the comparison condition;

    3) A single-line operator corresponds to a single-line subquery, and a multi-line operator corresponds to a multi-line subquery;

1. Single row subquery:

    

2. Use the group function in a one-line function:

    

3. Having statement in subquery: For the difference between where and having, please refer to --> Difference between where and having in Oracle

4. Multi-line subquery:

    Multi-line comparison operators:

operator	meaning
IN	equal to any value in the list
ANY	Compare with any value returned by the subquery
ALL	Compare with all values ​​returned by the subquery

5. Use ANY in multi-line subquery: query employee information with higher salary than any employee in department 10

    

6. Use ALL for multi-line subquery: query the information of employees whose salary is higher than that of all employees in No. 10 department

    

7. Use in for multi-line subqueries: query information about employees who are not leaders

    

※ Unselected row: Indicates that there is no data that meets the conditions