Oracle 1z0-071 Exam With Confidence Using Practice Dumps

For the provided DELETE statement with an EXISTS clause:

Option B: The subquery is executed before the DELETE statement is executed.

Subqueries with EXISTS are typically executed before the outer DELETE statement to determine which rows of the outer query satisfy the condition.

Option D: The DELETE statement executes successfully even if the subquery selects multiple rows.

The EXISTS condition is used to check for the existence of rows returned by the subquery, regardless of how many rows there are. It returns TRUE if the subquery returns at least one row.

Options A, C, and E are incorrect because:

Option A: This statement is incorrect; the subquery is indeed a correlated subquery because it references the employee_id from the outer query (employees).

Option C: This is incorrect because not all existing rows in the EMPLOYEES table will be deleted, only those for which an associated record exists in the emp_history table.

Option E: While technically the subquery may be evaluated multiple times, it is only executed for those rows in EMPLOYEES that satisfy the condition of the EXISTS clause.

B. SELECT product_id, (unit_price * 0.15 / (4.75 + 552.25)) FROM products; C. SELECT product_id, (expiry_date - delivery_date) * 2 FROM products; E. SELECT product_id, unit_price, unit_price + surcharge FROM products;

Comprehensive and Detailed Explanation WITH all References:

A. This is invalid because "Discount" is a string literal and cannot be used without quotes in an arithmetic operation. Also, there is a typo in unit_pricer, and 'discount' is not a defined column in the table. B. This is valid. It shows a mathematical calculation with unit_price, which is of NUMBER type. Division and multiplication are valid operations on numbers. C. This is valid. The difference between two DATE values results in the number of days between them, and multiplying this value by a number is a valid operation. D. This is invalid because expiry_date is of DATE type and cannot be multiplied by a number. Also, there's a typo: "SPLECT" should be "SELECT". E. This is valid. Both unit_price and surcharge are NUMBER types, and adding them together is a valid operation. F. This is invalid because concatenation operator || is used between a number (unit_price) and a string literal "Discount", which is not enclosed in single quotes, and 'discount' is not a defined column in the table.

In SQL, arithmetic operations on numbers and date arithmetic are valid expressions. Concatenation is also a valid expression when used correctly between string values or literals. Operations that involve date types should not include multiplication or division by numbers directly without a proper interval type in Oracle SQL.

These rules are detailed in the Oracle Database SQL Language Reference, where expressions, datatype precedence, and operations are defined.

Option D is the correct SQL statement that satisfies all the requirements mentioned. The CASE statement correctly compares the hire_date to date intervals subtracted from the current date (SYSDATE) to determine the number of years of service. This CASE statement is also appropriately ordered to ensure that the first condition matched is the one returned, preventing overlapping of the conditions.

Here is how Option D works according to the requirements:

It selects the last_name and hire_date from the employees table.

The CASE statement is used to calculate the number of years of service and to display the appropriate message according to the intervals defined.

The ORDER BY hire_date clause ensures the results are sorted by the date of hire.

In Option D, the intervals are defined in the correct order, ensuring that the first true condition is the one that is used:

The first WHEN checks if the hire date is 15 or more years ago.

The second WHEN checks if it is 10 or more years ago.

The third WHEN checks if it is 5 or more years ago.

The ELSE clause covers any hire dates less than 5 years ago.

The correct syntax for the intervals is SYSDATE - hire_date >= TO_YMINTERVAL('15-0') and similarly for the 10 and 5 years intervals.

Options A, B, and C are incorrect because they have various issues, such as incorrect ordering of the CASE statement's conditions, which could lead to incorrect results due to overlapping intervals, or the use of the TO_YMINTERVAL function that may not properly cover the intended date ranges.

References:

Oracle Documentation on CASE Expressions: SQL Language Reference - CASE Expression

Oracle Documentation on TO_YMINTERVAL Function: SQL Language Reference - TO_YMINTERVAL

Oracle Documentation on ORDER BY Clause: SQL Language Reference - ORDER BY Clause

Therefore, Option D is the statement that fulfills all the requirements for displaying the number of years of service based on the employee's hire date and ordered by the hire date.