Pass Using 1z0-071 Exam Dumps

INVISIBLE indexes are a feature in Oracle Database 12c and later versions that allow an index to be maintained but not used by the optimizer unless explicitly hinted.

A. False. An INVISIBLE index still consumes storage space as it is maintained in the background.

B. False. There is no such restriction. You can create multiple INVISIBLE indexes on the same column list.

C. False. The optimizer can consider INVISIBLE indexes if they are hinted at in the query.

D. True. You can alter the visibility of an index using the ALTER INDEX command to make an INVISIBLE index VISIBLE.

E. True. Even though they are invisible to the optimizer by default, all DML operations such as INSERT, UPDATE, and DELETE continue to maintain the index as they would with a VISIBLE index.

Based on the table structure given in the image, to return the value 'CUBE' from the 'bricks' table when joined with 'boxes', the condition must ensure that the weight of the bricks is within the allowed weight range specified in the 'boxes' table for a 'SMALL' box size.

A. True. Since MAX_WEIGHT is 0, a comparison using >= min_weight AND weight < max_weight will only return rows where the weight is less than 0, which is impossible for actual weight values, suggesting there might be a mistake in the data provided or the comparison logic.

E. True. NOT (weight > max_weight) effectively translates to 'where weight is less than or equal to max_weight'. However, since MAX_WEIGHT is 0, this condition would only be true if the weight is not greater than 0, which can only happen if the weight is 0 or less. This seems to indicate an anomaly where either the data is incorrect, or the condition is meant to handle a case where the weight is zero or possibly a negative placeholder value.

Both B and D will potentially return more than just 'CUBE' if there are bricks with weights greater than MIN_WEIGHT. C is incorrect because BETWEEN is inclusive, and there are no weights that are both greater than or equal to MIN_WEIGHT and less than or equal to MAX_WEIGHT when MAX_WEIGHT is 0.

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.

In Oracle SQL, the following syntactical rules apply:

A. This query will result in an error because there is no comma separating the column names FIRST_NAME and LAST_NAME. The correct syntax should include a comma to separate the column names in the SELECT list.

B. This query is correctly formatted with a comma separating the column names, so it will not result in an error.

C. This query will result in an error because an alias defined in the SELECT list (ANNUAL_SALARY) cannot be used in the WHERE clause of the same query level. It must be repeated in the WHERE clause as 12 * SALARY.

D. This query will execute successfully because 12 * SALARY is directly used in the WHERE clause, and ANNUAL_SALARY is used in the ORDER BY clause, which is allowed.

E. This query is correct and will not result in an error. It uses 12 * SALARY in both the WHERE and ORDER BY clauses.

F. Similar to option C, this query will execute successfully because ANNUAL_SALARY is correctly used in the ORDER BY clause, and the WHERE clause does not attempt to reference the alias.

References:

Oracle Database SQL Language Reference, 12c Release 1 (12.1): "Database Object Names and Qualifiers"