Oracle 1z0-071 Based on Real Exam Environment

Regarding the properties and capabilities of virtual columns in Oracle Database:

• C. They can be indexed: In Oracle, virtual columns can indeed be indexed. This allows for performance optimization on queries that utilize these columns, despite the fact that their values are derived and not stored physically.
• D. They cannot have a data type explicitly specified: The data type of a virtual column is derived from the expression used to define it. Therefore, it is not specified explicitly but is inferred from the expression itself.

Incorrect options:

• A: Virtual columns cannot be referenced in the WHERE clause of UPDATE or DELETE statements because they are not stored and cannot be individually modified.
• B: Virtual columns cannot be referenced in the SET clause of an UPDATE statement since they are derived from other column values and cannot be updated directly.
• E: Virtual columns cannot reference other virtual columns in their expressions due to the potential for recursive and complex dependencies.

For SQL queries involving set operations like UNION, UNION ALL, INTERSECT, and MINUS, the data types and number of columns in the SELECT statements being combined must be the same. Here is a breakdown of each query option:

• Option A: This query successfully combines results from two tables using UNION ALL, which combines all rows from both SELECT statements, including duplicates. Both queries select two columns (prod_id and exp_date, with exp_date being NULL in the second query). This is valid as the number of columns and their data types match.
• Option B: This query attempts to use INTERSECT, which returns only the rows common to both SELECT statements. However, the first SELECT statement chooses prod_id and prod_name, while the second only substitutes a constant value for prod_id without specifying from which table it selects prod_name. If "newproducts" (presumably a typo and should be "new_products") does not have the exact columns as "products", or if the data types do not match, it will fail.
• Option C: This query uses UNION, which removes duplicates from the combined dataset. The use of SELECT * assumes that both "products" and "new_products" tables have the same columns in the same order with matching data types. This query will succeed if those conditions are met.
• Option D: This query uses MINUS to subtract results of the second SELECT from the first. However, it fails because 'k' does not explicitly match a column name in "products", suggesting a potential error unless 'k' is indeed a valid column.
• Option E: This query fails because the first SELECT statement fetches only one column (prod_id) while the second fetches two columns (prod_id and prod_name). UNION ALL requires the same number of columns with compatible types in all SELECT statements involved.

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.

To calculate the length of employment, you would compare the current date to the HIRE_DATE and calculate the difference in years.

A. This is the correct answer. The expression calculates the number of days between the current date (SYSDATE) and the HIRE_DATE, then divides by 365 to convert it to years, and checks if it is greater than 5.

B. SYSTIMESTAMP includes a time component including fractional seconds and time zone information, making this comparison incorrect.

C. There are typos in this option (CUARENT_DATE should be CURRENT_DATE and hire_data should be hire_date). Even with the correct function and column names, CURRENT_DATE returns the current date in the session time zone, not in years.

D. There are typos in this option (SYSNAYW should be SYSDATE). Additionally, dividing by 12 incorrectly assumes that a month is equivalent to a year.

E. This is a repetition of option D with the same issues.

F. There are typos in this option (CUNACV_DATE should be CURRENT_DATE and hire_data should be hire_date). Additionally, dividing by 12 incorrectly assumes that a month is equivalent to a year.

References:

• Oracle Database SQL Language Reference, 12c Release 1 (12.1): "Date Functions"