1z0-071 Exam Dumps - Oracle Database 12c SQL

In Oracle SQL, substitution variables (&1) can be used to dynamically replace a value in a SQL statement at runtime. To avoid being prompted for a value when executing a query that includes a substitution variable:

A. Use the DEFINE command before executing the query: By setting a value for a substitution variable using the DEFINE command, Oracle will use this value instead of prompting the user for input.

D. Execute the SET VERIFY OFF command before executing the query: The SET VERIFY OFF command suppresses the prompt for substitution variables by turning off the verification feature. This makes Oracle use the currently defined value for the variable.

References:

Oracle Database SQL Language Reference 12c, particularly the sections on substitution variables, the DEFINE command, and the SET command.

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.

To achieve the desired output for the query from the MEMBERS table:

C. ORDER BY 1, LNAME DESC: This clause correctly sorts the results first by the first column (city) in ascending order by default, and then by the alias LNAME (last_name) in descending order.

E. WHERE city LIKE '%AN%': This clause correctly filters the rows to include only those cities containing the string 'AN' anywhere in the city name, using the LIKE operator which is suitable for pattern matching.

Incorrect options:

A: This would order both columns in ascending order, which does not meet the requirement for last_name to be in descending order.

B: This misplaces the order priorities and uses explicit column names that contradict the sorting requirement specified.

D: Incorrect syntax for a LIKE clause; equality operator cannot be used with wildcards.

F: The IN operator is incorrectly used here with a pattern, which is not valid syntax.

The query uses TO_CHAR and NEXT_DAY functions to format and determine dates:

B. It returns the date for the first Monday of the next month: The function NEXT_DAY(LAST_DAY(SYSDATE), 'MON') finds the next Monday after the last day of the current month, effectively giving the first Monday of the next month. The TO_CHAR formatting is used to return this in a readable format.

When performing DML operations on a view, certain restrictions apply:

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: If the defining query of a view contains the DISTINCT keyword, it cannot be used for certain DML operations, such as INSERT and UPDATE, because the set of rows it represents is not directly modifiable.

E. Views cannot be used to add or modify rows in an underlying table if the defining query of the view contains aggregating functions: Aggregating functions create a result that summarises multiple rows and cannot be reversed to point to a single row for modification.

F. 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: If a column with a NOT NULL constraint is not included in the view's defining query, and it does not have a default value, it is not possible to insert through the view because it would violate the NOT NULL constraint.

References:

Oracle Database SQL Language Reference 12c, particularly the sections on views and the restrictions on DML operations through views.

C. True, the data dictionary is constantly updated to reflect changes to the metadata of the database objects, permissions, and structures, among other things.E. True, the SYS user owns all base tables in the data dictionary. These base tables underlie all data dictionary views that are accessible by the users.

A, B, and D are not correct because: A. Base tables do not necessarily have the prefix DBA_; instead, DBA_ is a prefix for administrative views that are accessible to users with DBA privileges. B. The data dictionary records metadata about the actions, not the actions themselves. D. Not all users have access to all information in the data dictionary. Access is controlled by privileges.

References:

Oracle documentation on data dictionary and dynamic performance views: Oracle Database Reference

Understanding the Oracle data dictionary: Oracle Database Concepts

The UNION ALL operator in SQL combines the results of two or more SELECT statements into a single result set:

Option A: True. Since UNION ALL does not eliminate duplicates, it does not ignore NULLs during any duplicate checking; however, it's worth noting that UNION ALL does not perform duplicate checking at all.

Option B: False. Unlike the UNION operator, UNION ALL does not eliminate duplicates; it includes all duplicates in the output.

Option C: False. The column names do not need to be identical in each SELECT statement; however, the result set will use the column names from the first SELECT statement.

Option D: True. For UNION ALL to work correctly, the number of columns and their data types in each SELECT statement must match, but the column names can differ.

Option E: False. UNION ALL does not inherently sort the output; it merely combines the results as they are retrieved. Any sorting would need to be explicitly specified using an ORDER BY clause.

The query uses the syntax GROUP | BY 1 which is not correct. The pipe symbol | is not a valid character in the context of the GROUP BY clause. Additionally, when using GROUP BY with a number, it refers to the position of the column in the SELECT list, which should be written without a pipe symbol and correctly as GROUP BY 1. Since the syntax is incorrect, the database engine will return an error.