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databases Online Quiz - 134

Description: databases Online Quiz - 134
Number of Questions: 20
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Tags: databases
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You are managing constraints on a table in Oracle. Which of the following choices correctly identifies the limitations on check constraints?

  1. Values must be obtained from a lookup table.

  2. Values must be part of a fixed set defined by create or alter table.

  3. Values must include reserved words, such as SYSDATE and USER.

  4. The column cannot contain a NULL value.


Correct Option: B

AI Explanation

To answer this question, you need to understand the concept of check constraints in Oracle.

Check constraints in Oracle allow you to define a condition that must be true for each row in a table. This condition is specified as an expression, and it can reference multiple columns in the table. The purpose of a check constraint is to ensure that the data in the table meets certain criteria.

Let's go through each option to understand why it is correct or incorrect:

Option A) Values must be obtained from a lookup table. This option is incorrect because check constraints in Oracle do not require values to be obtained from a lookup table. The values can be any valid expression that evaluates to true or false.

Option B) Values must be part of a fixed set defined by create or alter table. This option is correct. Check constraints in Oracle can be used to enforce that the values in a column must be part of a fixed set defined by the create or alter table statement. This means that the values must be explicitly specified and cannot be any arbitrary values.

Option C) Values must include reserved words, such as SYSDATE and USER. This option is incorrect. Check constraints in Oracle do not require values to include reserved words. The values can be any valid expression that evaluates to true or false.

Option D) The column cannot contain a NULL value. This option is incorrect. Check constraints in Oracle can allow NULL values in a column. Whether or not NULL values are allowed is determined by the NULL or NOT NULL constraint, not the check constraint.

The correct answer is B) Values must be part of a fixed set defined by create or alter table. This option is correct because it accurately describes one of the limitations on check constraints in Oracle.

The transaction control that prevents more than one user from updating data in a table is which of the following?

  1. lock

  2. commit

  3. rollback

  4. savepoint


Correct Option: A

AI Explanation

To answer this question, you need to understand transaction control in database management systems.

Option A) Lock - This option is correct because locks are used to prevent more than one user from updating data in a table simultaneously. Locks are acquired on the table or specific rows and are released after the transaction is complete.

Option B) Commit - This option is incorrect because the commit operation is used to permanently save the changes made during a transaction. It does not prevent multiple users from updating data simultaneously.

Option C) Rollback - This option is incorrect because the rollback operation is used to undo the changes made during a transaction and restore the database to its previous state. It does not prevent multiple users from updating data simultaneously.

Option D) Savepoint - This option is incorrect because savepoints are used to mark a specific point within a transaction to which it can be rolled back. It does not prevent multiple users from updating data simultaneously.

The correct answer is A) Lock. This option is correct because locks are used to prevent more than one user from updating data in a table simultaneously.

You are using SQL operations in Oracle. All of the following DATE functions return a DATE datatype except one. Which one is it?

  1. NEW_TIME

  2. LAST_DAY

  3. ADD_MONTHS

  4. MONTHS_BETWEEN


Correct Option: D

Which operator will be evaluated first in the following SELECT statement?

  1. +

  2. *

  3. /

  4. _


Correct Option: B

Which datatype stores data outside Oracle Database?

  1. UROWID

  2. BLOB

  3. NCLOB

  4. BFILE


Correct Option: D

Which of the following statements are true?

  1. Primary key constraints allow NULL values in the columns.

  2. Unique key constraints allow NULL values in the columns.

  3. Primary key constraints do not allow NULL values in the columns.

  4. A nonunique index cannot be used to enforce primary key constraints.


Correct Option: B,C

At a minimum, how many join conditions should be there to avoid a Cartesian join if there are three tables in the FROM clause?

  1. 1

  2. 2

  3. 3

  4. There is no minimum.


Correct Option: B

What is ASM?

  1. an integrated file system only

  2. A mirroring technology only

  3. an integrated file system with a volume manager

  4. A Volume manager only


Correct Option: C

AI Explanation

To answer this question, you need to understand what ASM stands for and its purpose.

ASM stands for Automatic Storage Management. It is a feature provided by Oracle Database that combines the functionalities of a volume manager and a file system.

Option A) an integrated file system only - This option is incorrect because ASM is not just an integrated file system. It also includes volume management capabilities.

Option B) A mirroring technology only - This option is incorrect because ASM is not solely a mirroring technology. While it does provide mirroring capabilities, it also includes volume management and file system functionalities.

Option C) an integrated file system with a volume manager - This option is correct. ASM combines the functionalities of a volume manager and a file system, allowing for efficient management and allocation of storage resources.

Option D) A Volume manager only - This option is incorrect because ASM is not only a volume manager. It also includes file system functionalities.

The correct answer is C) an integrated file system with a volume manager. This option is correct because it accurately describes the capabilities of ASM.

The daemon that is required to enable synchronization between ASM and its client database instances is

  1. CRS

  2. CSS

  3. ocsssd

  4. ocsd.bin


Correct Option: B

File types not supported by ASM is:

  1. trace files

  2. cross paltform transportable datafiles

  3. change tracking file

  4. temporary files


Correct Option: A

In ASM, Mirroring is done at ___________ level.

  1. tablespace

  2. data blocks

  3. file

  4. extents


Correct Option: D

ASM divides files into ______ extents.

  1. 1MB

  2. 10MB

  3. 100KB

  4. 10KB


Correct Option: A

What is Oracle data guard?

  1. used for data refresh from Production env. to development env.

  2. used as security layer to protect data from unathorized access.

  3. An Oracle technology used for data protection through mirroring.

  4. It ensures high availability, data protection, and disaster recovery for enterprise data.


Correct Option: D

A Data Guard configuration contains one production database which is _____________

  1. a RAC database only

  2. a stand alone database only

  3. The primary database can be either a standalone database or a RAC.

  4. a physical standby database .


Correct Option: C

The three dataguard services are:

  1. redo transport service,log applyservice,Role transition

  2. log applyservice,Role transition,Failover service

  3. redo transport service,Role transition,Failover service

  4. redo transport service,log applyservice,Failover service


Correct Option: A

The Command line interface for Data Guard is ________________

  1. DGMGRL

  2. DGCMD

  3. DGBKR

  4. DGGRL


Correct Option: A

The Protection modes available in Data guard are:

  1. Protection,availability,performance

  2. Protection,availability,scalability

  3. Maximum Protection,maximum availability,maximum performance

  4. Maximum Protection,maximum availability,maximum scalability


Correct Option: C

Which component in the SGA has the dictionary cache?

  1. Buffer cache

  2. Library cache

  3. Shared pool

  4. Program Global Area


Correct Option: C

What is the minimum number of control files are required to start a database?

  1. One

  2. Two

  3. Three

  4. None


Correct Option: A
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