databases Online Quiz - 229
|Description: databases Online Quiz - 229|
|Number of Questions: 20|
|Created by: Aliensbrain Bot|
Which of the following events can be used to fire triggers?
Which of the following queries can you use to search for employees with the pattern 'A_B' in their names?
To write a query that performs an outer join of tables A and B and returns all rows from B, You need to write
To answer this question, you need to understand the concept of outer joins.
An outer join is used to combine records from two tables, even if there is no match between the columns being joined. There are three types of outer joins: left outer join, right outer join, and full outer join.
In this case, the question asks for a query that returns all rows from table B. To achieve this, you need to perform a right outer join.
Option A) Any outer join - This option is incorrect because it is too general and does not specify the type of outer join required.
Option B) Left outer join - This option is incorrect because a left outer join would return all rows from table A, not table B.
Option C) Cross join - This option is incorrect because a cross join returns the Cartesian product of the two tables, which is not what the question asks for.
Option D) Right outer join - This option is correct because a right outer join combines all rows from table B, even if there is no match in table A.
Therefore, the correct answer is D) a right outer join.
15 Examine the description of the STUDENTS table: STD_ID NUMBER (4) COURSE_ID VARCHAR2 (10) START_DATE DATE END_DATE DATE Which two aggregate functions are valid on the START_DATE column? (Choose two)
You would like to display the system date in the format "Monday, 01 June, 2001". Which SELECT statement should you use?
Which two statements complete a transaction? (Choose two.)
To complete a transaction, there are typically two statements involved: COMMIT and ROLLBACK.
Let's go through each option to determine which two statements complete a transaction:
A. DELETE employees; This statement is used to delete data from a table but does not complete a transaction.
B. DESCRIBE employees; This statement is used to describe the structure of a table but does not complete a transaction.
C. ROLLBACK TO SAVEPOINT C; This statement is used to rollback a transaction to a specific savepoint, effectively undoing all changes made after that savepoint. This is one of the statements that completes a transaction.
D. ALTER TABLE employees SET UNUSED COLUMN sal; This statement is used to mark a column as unused in a table, but it does not complete a transaction.
E. GRANT SELECT ON employees TO SCOTT; This statement is used to grant select privileges on a table to a user, but it does not complete a transaction.
Based on the above analysis, the two statements that complete a transaction are:
C. ROLLBACK TO SAVEPOINT C; D. ALTER TABLE employees SET UNUSED COLUMN sal;
Therefore, the correct answer is C and D.
Which command will delete all data from a table and will not write to the rollback segment?
Which Oracle access method is the fastest way for Oracle to retrieve a single row?
Which character function can be used to return a specified portion of a character string?
To produce a meaningful result set without any cartesian products, what is the minimum number of conditions that should appear in the WHERE clause of a four-table join?