Pass the Oracle Oracle PL 1z0-071 Questions and answers with CertsForce

A: This is true. Using PURGE in the DROP TABLE command will permanently remove the table and its dependent objects so that it cannot be recovered, and the action cannot be rolled back.

B: This statement is true. Dropping the base table will result in the removal of all views that are based on the DEPARTMENTS table.

C: This statement is false. The PURGE option removes the table and does not just delete rows.

D: This statement is true. The DROP TABLE command will remove the DEPARTMENTS table from the database.

E: This statement is true. When a table is dropped, all synonyms for that table are also removed.

F: This statement is true. Dropping a table will automatically drop all indexes associated with the table.

Performance implications related to non-equijoin SQL statements in Oracle Database are often a topic of optimization:

C. The join syntax used makes no difference to performance: In Oracle Database, the performance of a query involving joins is typically more dependent on factors like the underlying data distribution, indexes, optimizer statistics, and system configuration rather than the syntax (ANSI vs Oracle traditional syntax). The optimizer in Oracle is sophisticated enough to interpret different syntactical expressions of joins and optimize them accordingly.

References:

Oracle Database Performance Tuning Guide 12c, which discusses the impact of different join syntaxes and how Oracle's optimizer handles them.

The UNION ALL operator in SQL is used to combine the results of two or more SELECT statements:

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

UNION ALL does not eliminate duplicates; it simply combines all rows from the queries provided.

Options A, B, and C are incorrect as they describe behaviors of other set operators:

Option A: Describes the behavior of INTERSECT, not UNION ALL.

Option B: Describes the behavior of UNION, not UNION ALL.

Option C: Describes the behavior of EXCEPT or MINUS, not UNION ALL.

The data dictionary is a read-only set of tables that provides information about the database. Certain operations that modify the database structure will cause changes to the data dictionary:

Option B: GRANT UPDATE ON scott.emp TO fin_manager;

Granting privileges on a table will change the data dictionary as it records the new privilege.

Option D: TRUNCATE TABLE emp;

Truncating a table affects the data dictionary because it removes all rows from a table and may also reset storage parameters.

Options A, C, and E do not cause changes to the data dictionary:

Option A is incorrect because the DELETE command modifies data, not the data dictionary structure.

Option C is incorrect because altering a session parameter does not change the data dictionary; it is a temporary change for the session.

Option E is incorrect because a SELECT query does not change the database, it just retrieves information.

The TO_CHAR function is used to convert a number to a string format in Oracle SQL. In this format mask '$9,999', the dollar sign is a literal, and the 9 placeholders represent a digit in the output. The comma is a digit group separator.

A. This statement is incorrect because the format model does not have enough digit placeholders to display the full number 1023.99; it would round it to $1,023 not $1,024. B. This statement is correct. Given the format '$9,999', the number 1023.99 will be formatted as $1,023 because the format rounds the number to no decimal places. C. This is incorrect because the format '$9,999' cannot display the number 10235.99; it exceeds the format's capacity. D. This is incorrect for the same reason as C, and the format would not change the thousands to hundreds. E. This statement is correct. If the number exceeds the maximum length of the format mask, which is 4 digits in this case, Oracle SQL displays a series of hash marks (#) instead of the number.

These formatting rules are described in the Oracle Database SQL Language Reference, which covers the TO_CHAR function and its number formatting capabilities.

A: True. The DBTIMEZONE function returns the database's time zone offset from UTC (Coordinated Universal Time). In Oracle 12c, DBTIMEZONE can return the time zone of the database in terms of a region name or as a numeric offset from UTC. This is stated in the Oracle documentation for managing time zones.

B: True. TIMESTAMP WITH LOCAL TIME ZONE is a data type that adjusts the data stored in the database to the time zone of the session that is querying or inserting the data. When data is stored, Oracle converts it from the session time zone to UTC, and upon retrieval, it converts it back to the session time zone. This is a feature designed to allow the same data to be viewed in different time zones automatically, making it highly useful in global applications.

D: True. SESSIONTIMEZONE function returns the time zone offset of the current session from UTC. This is useful for understanding and managing data conversions in applications that are used across different time zones. The time zone can be displayed as an offset from UTC or as a named region depending on the environment settings.

To determine which queries will execute successfully, we need to consider the compatibility of the column definitions and the structure of the SELECT statements:

Option A uses the MINUS set operator, which subtracts rows returned by the second SELECT statement from the rows returned by the first. For MINUS to work, the number and the order of columns and their data types must be the same in both queries. This query will not execute successfully because the second SELECT statement does not include all columns from the first SELECT statement, and the data types and sizes of PROD_ID do not match (CHAR(2) vs CHAR(4)).

Option B uses the UNION ALL set operator, which appends the results of the second SELECT statement to the results of the first. Unlike UNION, UNION ALL does not eliminate duplicate rows. This query will execute successfully because UNION ALL does not require the same data types or sizes, and the result will contain all columns from the first SELECT statement filled with NULL for non-matching columns from the second SELECT statement.

Option C uses the UNION set operator, which requires the same number of columns and compatible data types. This query will not execute successfully because PROD_NAME has different data types (CHAR(4) vs VARCHAR2(10)), and the result of a UNION must have the same number of columns with compatible data types in the two SELECT statements.

Option D uses the UNION set operator as well, but unlike Option C, it does not require a specific data type match because both SELECT statements include all columns and UNION is used (which will automatically handle type conversion where necessary). This query will execute successfully.

Option E uses the INTERSECT set operator, which requires the same number and order of columns and their data types to be identical or compatible. This query will not execute successfully because the data types and sizes of PROD_ID do not match (CHAR(2) vs CHAR(4)).

References:

Oracle Documentation on Set Operators: SQL Language Reference - Set Operators

Oracle Documentation on Data Type Precedence: SQL Language Reference - Data Type Precedence

In conclusion, only Option B and Option D will execute successfully because they adhere to the rules of the UNION ALL and UNION operators respectively, regarding column count and data type compatibility.

Oracle synonyms are used to simplify the referencing of complex schema objects:

Option A: Incorrect. A synonym cannot have another synonym; it directly references the base object.

Option B: Incorrect. A synonym does not have an object number as it is merely an alias for another object.

Option C: Correct. Any user with sufficient privileges can create a public synonym, which is accessible to all users in the database.

Option D: Incorrect. All private synonym names must be unique within a schema but not across the entire database.

Option E: Correct. Synonyms can be created for objects within packages, such as procedures or functions, simplifying the referencing of these objects without needing to specify the full package name.

For creating tables and utilizing sequences in Oracle 12c SQL, certain rules apply:

Option A: This statement is valid. It creates a table with a primary key and dates, where the default value for end_date is SYSDATE. There are no constraints on sequences, and all syntax is correct.

Option B: This option is invalid because it attempts to use CURRVAL of a sequence as a default value for a primary key. CURRVAL cannot be used until the sequence's NEXTVAL has been called in the session.

Option C: Invalid syntax because 'start date' is not a recognized default expression in Oracle SQL. If the intention was to use 'start_date' as a reference, it still would not work correctly without proper syntax for conditional default values.

Option D: This syntax is invalid in Oracle SQL because the DEFAULT clause does not support relational conditions directly within the table definition.

Option E: Valid. It correctly uses NEXTVAL for a sequence in the DEFAULT clause for the primary key, ensuring that each new record has a unique primary key generated from the sequence. The start_date and end_date are assigned defaults of SYSDATE, which is syntactically correct.

When you need to compare dates and calculate the difference in months between two dates, you use the MONTHS_BETWEEN function in Oracle SQL.

A. This statement is incorrect because MONTHS_BETWEEN takes the later date first, then the earlier date.

B. This statement is correct. The MONTHS_BETWEEN function returns the number of months between two dates. It takes the later date (in this case, SYSDATE) first and the earlier date (start_date) second. If the start_date is within the last 25 months, the result will be less than or equal to 25.

C. This statement is incorrect. The expression TO_NUMBER(start_date - SYSDATE) would not give the correct number of months between the dates.

D. This statement is incorrect. The ADD_MONTHS(start_date, 25) function adds 25 months to start_date, and comparing it to SYSDATE would show dates that are at least 25 months in the future.