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

A: No implicit conversion is done here because TO_CHAR is an explicit conversion from a numeric to a string data type.

B: Implicit conversion happens here because the '0001' string will be automatically converted to a numeric data type to match the CUSTOMER_ID field.

C: No implicit conversion is needed because 0001 is already a numeric literal.

D: Implicit conversion occurs here because the string '01-JAN-19' will be converted to a date type to compare with INSERT_DATE.

E: No implicit conversion; DATE is explicitly specified using the DATE keyword.

F: Incorrect syntax, it has typographical errors and also TO_DATE is an explicit function, not an implicit conversion.

References for SQL functions, conversions, and the CROSS JOIN behavior can be found in the Oracle Database SQL Language Reference 12c documentation.

B: True. The second ROLLBACK command would not do anything because the first ROLLBACK TO SAVEPOINT a; already undid the delete operation, and there was no other DML operation between the first and the second ROLLBACK.

E: True. The second ROLLBACK command undoes the insert because after the first ROLLBACK TO SAVEPOINT a; there are no savepoints defined, so a subsequent ROLLBACK would undo all transactions to the beginning of the current session or last COMMIT.

The ROLLBACK command is used to undo transactions that have not yet been committed. Rolling back to a savepoint only undoes transactions up to that savepoint, and a subsequent ROLLBACK without a savepoint name will undo all uncommitted changes since the last COMMIT.

References:Oracle SQL documentation on the ROLLBACK statement provides details on how it interacts with savepoints and the effects it has on the transactions within a session.

Given the requirement to list PRODUCT_ID, SUPPLIER_ID, and QUANTITY_ON_HAND for products with QUANTITY_ON_HAND less than five:

B. This query correctly joins the two tables on PRODUCT_ID and filters rows where QUANTITY_ON_HAND is less than five. However, the syntax presented here might be incorrect due to improper placement of the condition within the ON clause; it should be in a WHERE clause.

D. This query correctly joins the two tables on PRODUCT_ID and applies the condition in a WHERE clause, which is the proper way to filter rows after performing the join.

Incorrect options:

A: The syntax uses NATURAL JOIN and AND incorrectly; also, conditions should be in a WHERE clause, not combined with the JOIN clause.

C: Similar to A, this option incorrectly places a condition directly in the JOIN clause without using a WHERE clause.

B. True. Oracle databases guarantee read consistency at the transaction level, meaning that each query can only see data that has been committed before the query began executing.

C. True. When an UPDATE statement is executed, Oracle locks each row as it is updated to prevent other transactions from modifying it until the transaction is committed or rolled back.

A is incorrect because updates made by one user cannot be rolled back by another user. D is incorrect because a query can access tables in other schemas if proper permissions are granted. E is incorrect because a user can own only one schema, which has the same name as the user in an Oracle database.

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.

In Oracle SQL, when performing a JOIN operation, the ON clause is used to specify the condition that relates the two tables being joined. The WHERE clause can be used to further filter the result set.

A) This is a valid join condition using the WHERE clause to filter the rows after the join has been made.

B) This statement will fail because the ON clause should only contain conditions that relate the two tables. The condition for filtering the departments table should be in the WHERE clause, not in the ON clause. This is a common mistake when writing JOIN statements.

C) This is a correct statement. The ON clause specifies how the tables are related and the WHERE clause specifies an additional filtering condition for the query.

D) This statement is also correct. It's similar to the first statement (A) and properly places the department_id filter in the ON clause, which is acceptable though not typically best practice as it can be less readable than using a WHERE clause for non-join conditions.

When the JOIN operation is executed, the database first pairs rows from the joined tables that meet the join condition specified by the ON clause. Then, it filters the result of the JOIN operation based on the condition specified in the WHERE clause.

References:

Oracle Documentation on Joins: https://docs.oracle.com/database/121/SQLRF/queries006.htm#SQLRF52359

The correct statement for computing the total annual compensation for each employee is option C. This is because the monthly commission is a percentage of the monthly salary (indicated by the column name MONTHLY_COMMISSION_PCT). To calculate the annual compensation, we need to calculate the annual salary (which is monthly_salary * 12) and add the total annual commission to it.

Here's the breakdown of the correct statement, option C:

(monthly_salary * 12) computes the total salary for the year.

NVL(monthly_commission_pct, 0) replaces NULL values in the monthly_commission_pct column with 0, ensuring that the commission is only added if it exists.

(monthly_salary * 12 * NVL(monthly_commission_pct, 0)) computes the annual commission by first determining the monthly commission (which is a percentage of the monthly salary), and then multiplying it by 12 to get the annual commission.

Finally, (monthly_salary * 12) + (monthly_salary * 12 * NVL(monthly_commission_pct, 0)) adds the annual salary and the annual commission to get the total annual compensation.

The other options are incorrect:

Option A is incorrect because it adds the monthly_commission_pct directly to the monthly_salary, which does not consider that monthly_commission_pct is a percentage.

Option B is incorrect because it adds the commission percentage directly without first applying it to the monthly salary.

Option D is incorrect because it does not handle the NULL values in the commission column, which would result in a NULL total annual compensation whenever the monthly_comission_pct is NULL.

References:

Oracle Documentation on NVL function: NVL

Oracle Documentation on Numeric Literals: Numeric Literals

E. True. Both & and && can prefix substitution variables in queries as well as in DML statements. & is used for defining a substitution variable that prompts the user every time the variable is encountered. && is used for a persistent substitution variable that, once defined in the session, will not prompt the user again for a value if used subsequently.