1z0-071 Exam Dumps - Oracle PL Questions and Answers

When using the TRUNCATE TABLE command in Oracle, several aspects of the table's structure and associated database objects are impacted. Here's an explanation of each option:

A: Incorrect. TRUNCATE TABLE does not drop triggers associated with the table; they remain defined.

B: Correct. Indexes on the table are retained and not dropped when you truncate a table. However, if the index is a domain index, it may be dropped depending on its type.

C: Correct. Integrity constraints such as primary keys, foreign keys, etc., are retained unless they are on a disabled state where truncation can lead to constraint being dropped.

D: Incorrect. A TRUNCATE TABLE operation cannot be rolled back. It is a DDL (Data Definition Language) operation and commits automatically.

E: Incorrect. The TRUNCATE TABLE operation deallocates the space used by the data unless the REUSE STORAGE clause is specified.

F: Incorrect. TRUNCATE TABLE operation removes all the rows in a table and does not log individual row deletions, thus FLASHBACK TABLE cannot be used to retrieve the data.

When performing DML operations on a view without INSTEAD OF triggers:

Option C: Views cannot be used to add rows to an underlying table if the table has columns with NOT NULL constraints lacking default values which are not referenced in the defining query of the view.

This is true because the view would not provide values for NOT NULL columns without defaults, leading to an error.

Option D: Views cannot be used to add or modify rows in an underlying table if the defining query of the view contains the DISTINCT keyword.

Using DISTINCT in the view’s defining query can make the view non-updatable, as it may aggregate multiple rows into one.

Option E: Delete statements can always be done on a table through a view.

Deletes through a view are typically unrestricted as long as the view does not involve aggregates, DISTINCT, or similar constructs that would logically preclude determining which underlying rows should be deleted.

For the provided UNION ALL query:

Option C: It will return rows from both SELECT statements including duplicate rows.

UNION ALL is used to combine the results of two SELECT statements and does not eliminate duplicates.

Options A, B, and D are incorrect because:

Option A: UNION ALL does not eliminate duplicate rows, unlike UNION.

Option B: This would be true for INTERSECT, not UNION ALL.

Option D: This would be true for EXCEPT or MINUS, not UNION ALL.

The CHECK constraint is generally used to limit the range of values that can be placed in a column. If a CHECK constraint exists on the department_id to only allow values such as 80 (assuming from the context provided):

A. UPDATE emp80 SET department_id=90 WHERE department_id=80: This UPDATE statement attempts to set the department_id to 90 for rows where it is currently 80. If there is a CHECK constraint preventing department_id from being anything other than 80, this statement would violate that constraint.

Incorrect options:

B: DELETE operations do not affect CHECK constraints as they do not involve modifying or setting column values.

C and D: SELECT statements do not modify data and thus cannot violate data integrity constraints like CHECK constraints.

C. True. A transaction that is interrupted by a system failure is automatically rolled back by Oracle to ensure data consistency. This is part of the ACID (Atomicity, Consistency, Isolation, Durability) properties that Oracle adheres to.

D. True. A ROLLBACK without specifying a savepoint rolls back the entire transaction and removes all savepoints within that transaction. This restores the data to the state it was in at the beginning of the transaction.

A: Insert statements can be done through a view only if all NOT NULL constraints without default values of the base table are included in the view. Therefore, statement A is incorrect.

B: The WITH CHECK OPTION ensures that all DML operations performed through the view result in data that conforms to the view’s defining query. It affects DELETE as well as other DML operations, making statement B incorrect.

C: Similar to inserts, DELETE operations can be done through a view unless the view contains constructs that inherently do not support it, such as certain joins or set operations. Statement C is generally incorrect.

D: If a view does not include all NOT NULL columns without defaults of the underlying table, it cannot be used to add rows because the missing columns will lack values. This makes statement D correct.

E: This statement is incorrect as primary keys do not affect querying through views; they affect insert and update operations where uniqueness and non-nullability are enforced.

F: If the defining query of a view includes DISTINCT, the view generally cannot be used to perform update or insert operations as it may not be able to uniquely determine rows. This makes statement F correct.

Examining the execution of SELECT statements in Oracle SQL requires understanding correct syntax, especially regarding aliases and string literals:

Option A: Incorrect. Although the syntax might seem plausible, using DATE as an alias without quotes can lead to ambiguity because DATE is a reserved keyword in Oracle SQL. This might cause an error or unexpected behavior unless it is enclosed in double quotes.

Option B: Incorrect. Single quotes are used for string literals in SQL, not for aliasing column names. Using single quotes for aliasing, as in 'CUSTOMER-ID', 'DUES', is syntactically incorrect and will result in an error.

Option C: Correct. This statement uses valid syntax with no reserved keywords as aliases and no misuse of string literal notation. Aliases are provided without quotes, which is acceptable as long as they are not reserved words or contain special characters.

Option D: Correct. It correctly uses double quotes for aliasing, which is necessary when using reserved words like "DATE" or special characters. This is a proper use of SQL syntax for aliasing in Oracle.

Option E: Incorrect. This statement attempts to use aliases with hyphens without enclosing them in double quotes, which leads to syntax errors. Also, customer id seems to be missing an underscore or another connector to properly reference a column name, indicating a typo or error.

For these queries, ensuring correct alias syntax and avoiding reserved keywords without appropriate quoting are key elements for successful execution.

Both ROUND and TRUNC functions can be applied to numbers, and MOD is a function that returns the remainder of a division. The ROUND function rounds a number to a specified number of decimal places, which can be positive, zero, or negative. The TRUNC function truncates a number to a specified number of decimal places.

ROUND(MOD(25,3),-1) rounds the result of MOD(25,3), which is 1, to tens place, which results in 0. TRUNC(MOD(25,3),-1) truncates the result of MOD(25,3), which is 1, to tens place, which also results in 0.

Both are valid, but in this specific case, they give the same result because the remainder (1) when rounded or truncated to tens place (-1) will be 0.

This SQL query checks for product IDs (prod_id) from the costs table where the promotion ID (promo_id) is associated with promotions whose costs are less than the maximum promotional cost of all promotions, grouped by the duration of each promotion (calculated as promo_end_date - promo_begin_date). The query is correctly written to fulfill these conditions.

The subquery SELECT MAX(promo_cost) FROM promotions GROUP BY (promo_end_date - promo_begin_date) computes the maximum cost of promotions grouped by their duration, returning the highest cost for each distinct promotion length.

The WHERE promo_cost < ALL (...) clause then filters out the promotions where the promo_cost is less than all of the maximum costs returned by the subquery, ensuring that only promo_ids associated with costs less than the highest cost for any promotion length are considered.

Since this logical structure correctly implements the given requirement, the statement executes successfully and yields the correct results.

The ORDER BY clause in Oracle SQL is used to sort the result set of a query by one or more columns, and it comes with its own set of rules and behaviors:

D. Column aliases can be used In the ORDER BY clause: True, column aliases that are specified in the SELECT clause can be used in the ORDER BY clause to refer to the columns to sort the results by.

E. In a character sort, the values are case-sensitive: Oracle sorts results in case-sensitive order by default when using the ORDER BY clause with character columns, unless otherwise specified by the NLS_SORT parameter.

References:

Oracle Database SQL Language Reference 12c, which provides details on sorting query results using ORDER BY.