Legit 1z0-071 Exam Download

D. All remaining employee names will appear in descending order F. The names of employees with maximum salary will appear first in descending order

Comprehensive and Detailed Explanation WITH all References:

Analyzing the given SQL query:

ORDER BY CASE WHEN salary = (SELECT max(salary) FROM employees) THEN 'A' ELSE last_name END, last_name DESC;

Here's what happens in the query:

• The CASE statement checks if the employee's salary is equal to the maximum salary in the table.
• If an employee has the maximum salary, they are assigned a constant value 'A', else their last_name is used for sorting.
• Since 'A' comes before any possible last name value in ascending order, all employees with the maximum salary will be listed first.
• After the CASE expression, the query specifies last_name DESC. This means that within each group sorted by the CASE expression, the names will be sorted in descending order.

Therefore, the employees with the maximum salary will appear first, and within that group, if there is more than one employee with the same maximum salary, they will be sorted in descending order by last name (F). Then, all remaining employee names will appear in descending order (D).

References:

• Oracle Documentation on CASE Expressions: CASE Expressions
• Oracle Documentation on Sorting Query Results: Sorting Query Results

In Oracle SQL, aggregation functions such as AVG and MAX cannot be nested directly inside each other and must be used in conjunction with GROUP BY on the column(s) that are not included in the aggregate function. Also, the HAVING clause filters groups after aggregation is applied.

A. This query will not execute successfully because it improperly nests MAX inside AVG. Oracle SQL does not allow this type of nested aggregation without a subquery.

B. This query will not execute successfully for the same reason as A, it improperly nests MAX inside AVG.

C. Similar to A and B, this query improperly nests SUM inside MAX, which is not allowed without a subquery.

D. This query will execute successfully. It filters rows based on the HIRE_DATE using a correct date format (assuming '9' refers to '09' or '1999' due to the NLS_DATE_FORMAT being 'DD-MON-RR'), then groups the remaining rows by DEPT_ID and calculates the sum of SALARY for each department.

E. This query will not execute successfully because it improperly nests MAX inside AVG without a subquery, and it incorrectly attempts to GROUP BY SALARY, which is already being aggregated.

References:

• Oracle Database SQL Language Reference, 12c Release 1 (12.1): "Aggregate Functions"
• Oracle Database SQL Language Reference, 12c Release 1 (12.1): "GROUP BY Clause"
• Oracle Database SQL Language Reference, 12c Release 1 (12.1): "HAVING Clause"

In a SELECT statement with DISTINCT, the ORDER BY clause can only order by expressions that are part of the SELECT list.

A. quantity alone is not sufficient to replace <clause> as it is not included in the SELECT list after DISTINCT.

B. This option can successfully replace <clause> because both quantity and unit_price are used in the SELECT expression, and thus their individual values are valid for the ORDER BY clause.

C. total_paid is an alias for the expression quantity * unit_price, but it cannot be used in the ORDER BY clause because Oracle does not allow aliases of expressions in DISTINCT queries to be used in ORDER BY.

D. product_id is not included in the SELECT list after DISTINCT and thus cannot be used in ORDER BY.

E. The expression quantity * unit_price is exactly what is selected, so it can replace <clause> and the query will complete successfully.

References:

• Oracle Database SQL Language Reference, 12c Release 1 (12.1): "ORDER BY Clause"

The correct way to compute the total annual compensation, which includes the monthly salary and the monthly commission (if any), is:

• Option C: SELECT last_name, (monthly_salary * 12) + (monthly_salary * 12 * NVL(monthly_commission_pct, 0)) AS annual_comp FROM employees;

Options A, B, and D are incorrect because:

• Option A: Does not handle the case where the commission percentage is NULL which would result in NULL for the entire expression when added to the monthly salary.
• Option B: Does not consider that the commission percentage might be NULL which could lead to incorrect calculations (or NULL values if commission is NULL).
• Option D: Incorrectly adds the monthly commission percentage directly to the annual salary without considering that the percentage needs to be applied to the salary.