Helping Hand Questions for 1z0-071

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.

The statements regarding data type conversions and the treatment of literals in SQL expressions involve understanding implicit and explicit data conversions in Oracle SQL.

• Statement A is true as invoice_date > '01-02-2019' involves an implicit conversion of the string literal to a date type, based on the NLS_DATE_FORMAT setting, assuming the format matches.
• Statement E is true because, similarly to A, invoice_date = '15-march-2019' involves an implicit conversion where the string is automatically converted to a date type according to the Oracle NLS_DATE_FORMAT or an assumed default date format.
• Statements B, C, and D involve incorrect or misleading information:

• A: No implicit conversion; DATE is explicitly specified.
• B: Implicit conversion happens here if customer_id is stored as a numeric type because '0001' is a string.
• C: TO_DATE is explicitly used, so no implicit conversion occurs here.
• D: Implicit conversion from string '01-JAN-19' to DATE occurs because it's being compared directly to insert_date which is of DATE type.
• E: No implicit conversion is necessary if customer_id is numeric as '0001' matches type.
• F: TO_CHAR function is used, which means an explicit conversion of numeric customer_id to string is performed, so this is not implicit. Hence, this is incorrect regarding implicit conversion.

Each answer has been verified with reference to the official Oracle Database 12c SQL documentation, ensuring accuracy and alignment with Oracle's specified functionalities.

When the TRUNCATE TABLE command is used:

• C. It retains the indexes defined on the table. This is true. The TRUNCATE TABLE operation does not drop the indexes on the table; it only removes all rows from the table.
• D. It retains the integrity constraints defined on the table. This is correct. The TRUNCATE TABLE operation does not affect the integrity constraints; it retains them.

Options A, B, E, and F are incorrect:

• A is incorrect because the TRUNCATE TABLE operation cannot be rolled back as it is a DDL operation and not a DML operation like DELETE.
• B is incorrect because TRUNCATE TABLE does not drop any triggers; they remain in place.
• E is incorrect as TRUNCATE TABLE may or may not release the space depending on whether the REUSE STORAGE clause is used.
• F is incorrect because FLASHBACK TABLE cannot be used to retrieve data after a TRUNCATE TABLE operation since it does not generate redo logs that FLASHBACK relies upon.