The given query is using the CROSS JOIN clause, which produces a Cartesian product of the tables involved. The DUAL table in Oracle is a special one-row, one-column table present by default in all Oracle database installations. When you cross join the DUAL table with itself multiple times without any where clause to limit the rows, the result is a multiplication of the row count for each cross-joined instance.

Since DUAL has a single row, cross-joining it with itself any number of times will still result in a single row being returned. The SELECT 2 part of the query simply dictates that the number 2 will be the value in the column of this single row.

So, the result of this query will be one row with a single column containing the value 2.

References:

Oracle Database SQL Language Reference 12c, especially sections on join operations and the DUAL table.

A. False. Constraints are enforced during INSERT and UPDATE operations, and by the nature of their definition, they impact DELETE operations as well (in the case of referential constraints).

B. False. A column with a foreign key constraint can contain a NULL value unless it is also constrained to be NOT NULL.

C. False. Not all constraints can be defined at the column level. For example, some constraints such as FOREIGN KEY constraints are more commonly defined at the table level.

D. True. A constraint can be disabled regardless of whether the constrained column contains data. However, re-enabling the constraint requires that all data satisfy the constraint rules.

E. True. A column with a UNIQUE constraint can indeed contain a NULL value, as NULL is considered not equal to any value, including itself. This means that multiple rows with NULL values do not violate the UNIQUE constraint.

References:

Oracle Documentation on Constraints: https://docs.oracle.com/database/121/SQLRF/clauses002.htm#SQLRF52271

Oracle Documentation on Enabling and Disabling Constraints: https://docs.oracle.com/database/121/ADMIN/clustrct.htm#ADMIN13508

A. Schema owners indeed can grant privileges on objects in their schema to other users or roles, making this statement true.

B. Roles in Oracle can be granted both object and system privileges, making this statement true as well.

C. Not all types of schema objects have associated object privileges. For example, synonyms do not have object privileges because they are just aliases for other objects.

D. The DBA role is a powerful role, but creating roles can be done by any user granted the necessary privileges, not just users with the DBA role.

E. Object privileges on a table do not automatically apply to all synonyms for that table. Synonyms are separate objects that must have privileges granted explicitly.

F. The privilege to grant system privileges is controlled by the GRANT ANY PRIVILEGE system privilege, making this statement true.

References:

Oracle Database SQL Language Reference, 12c Release 1 (12.1): " Privileges "

Oracle Database Security Guide, 12c Release 1 (12.1): " Administering User Privileges, Roles, and Profiles "

This question appears to be a duplicate of question no. 269, and the correct answers provided there apply here as well.

B. True. A DDL statement automatically commits any outstanding uncommitted transaction in the session. E. True. Exiting SQL*Plus without explicitly committing a transaction will cause the uncommitted transaction to be rolled back, not committed.

A, C, and D are incorrect for the same reasons provided in the explanation for question no. 269.

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.

Single-row functions in SQL return one result per row, and the following statements are true:

A: The data type of the returned value can indeed be different from the data type of the argument provided to the function. For example, the TO_CHAR function can take a numeric input and return a character string.

B: Single-row functions can be nested within each other to any level that is supported by Oracle. This means you can have a function call as an argument to another function, and so on.

E: The argument to a single-row function can be a column name, a variable, a literal, or an expression. This flexibility allows these functions to be very powerful in SQL expressions.

The incorrect options are:

C: Single-row functions do not return a single result row per table; they return a result for each row that is processed.

D: They are not limited to accepting only one argument. Some functions, like NVL , accept multiple arguments.

F: They are not limited to use in the WHERE clause; single-row functions can be used in any part of a SQL statement, including SELECT and ORDER BY clauses.

References:

Oracle Documentation on Single-Row Functions: SQL Functions

Synonyms in Oracle Database are aliases for database objects.

A. Correct. A synonym can be created for another synonym, essentially chaining synonyms. B. Incorrect. Private synonyms must be unique within a schema. However, because each user has their own schema, multiple users can have private synonyms with the same name, each pointing to objects in their respective schemas. C. Correct. Any user with the necessary privileges can create a PUBLIC synonym, which is accessible to all users. D. Incorrect. A synonym cannot be created for an object within a package, but it can be created for the package itself. E. Incorrect. Synonyms, like views, do not have object numbers because they do not occupy space in the database as tables do.

References can be found in the Oracle Database SQL Language Reference documentation, which details the rules and functionality of synonyms.

Regarding privileges in Oracle:

Option A : Dropping user FINANCE will automatically revoke SELECT on SCOTT.EMP from user FIN_CLERK.

Dropping a user will revoke all privileges that user has granted to others.

Option B : Revoking SELECT on SCOTT.EMP from user FINANCE will also revoke the privilege from user FIN_CLERK.

Since FINANCE granted SELECT on SCOTT.EMP to FIN_CLERK with grant option, revoking the privilege from FINANCE will also cascade and revoke it from FIN_CLERK.

Options C, D, and E are incorrect because:

Option C : User FINANCE can grant privileges it owns, but CREATE SESSION is a system privilege; unless FINANCE has the ' WITH ADMIN OPTION ' for CREATE SESSION, it cannot grant this privilege.

Option D : User FIN_CLERK can only grant privileges to others if it has been given those privileges with the ' WITH GRANT OPTION ' and it was not given in this case.

Option E : User FINANCE can grant privileges on SCOTT.EMP to other users only if it has those privileges with ' WITH GRANT OPTION ' . If the privilege was just SELECT with GRANT OPTION, it cannot grant ALL privileges.