Computer Knowledge

Database Management Systems

5,344 Questions

Database Management Systems (DBMS) form the core framework for data storage, retrieval, and security in modern software applications. Concepts such as the E-R model, backup planning, SQL integration, and big data architecture are essential for computer knowledge sections. This hub offers a comprehensive set of practice questions to master DBMS fundamentals and advanced database operations.

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Database Management Systems Questions

Multiple choice technology databases

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.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When joining three tables, you need at least 2 join conditions to avoid a Cartesian product. Each join condition connects two tables, so for N tables you need N-1 join conditions. With only 1 join condition for 3 tables, the third table would not be properly linked, creating a Cartesian product with the unjoined portion.

Multiple choice technology databases

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.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Oracle Data Guard ensures high availability, data protection, and disaster recovery for enterprise data by managing standby databases. Mirroring is a storage-level concept, data refresh is for copy management, and security layers protect access, none of which define Data Guard's core purpose.

Multiple choice technology databases

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 .
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

An Oracle Data Guard primary database serves as the production database and can be configured as either a single-instance standalone database or a multi-node Real Application Clusters (RAC) database. It is not limited to only RAC or standalone, and a physical standby is a backup copy, not the production database.

Multiple choice technology databases

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
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The three core components of Oracle Data Guard are Redo Transport Services (transferring redo data), Apply Services (applying redo data to standby databases), and Role Transitions (switchover and failover). Failover is a specific transition event, not an independent service category like redo transport or apply services.

Multiple choice technology databases

Which component of the SGA contains the parsed SQL code?

  1. Buffer cache

  2. Dictionary cache

  3. Library cache

  4. Parse cache
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

To answer this question, the user needs to have knowledge of Oracle's System Global Area (SGA) and its components. The SGA is a shared memory area that stores data and control information for Oracle database instances. The components of the SGA include the buffer cache, the shared pool, and the large pool.

The parsed SQL code is stored in the Library Cache, which is part of the shared pool. The Library Cache is a part of the SGA that stores shared SQL and PL/SQL areas. These areas contain parsed and executable forms of SQL and PL/SQL statements.

Therefore, the correct answer to this question is:

The Answer is: C. Library cache

Multiple choice technology databases

Which one is not mandatory background process ?

  1. DBWn (Writes the dirty buffers to datafiles)

  2. LGWR (writes the redo log buffer data to online redo log files)

  3. CKPT (An Event that flushes the modified data in buffer cache to disk and updates the controlfile and datafile)

  4. ARCn (Copies online redo log file to another location before they are overwritten)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

ARCn (Archiver process) is optional - databases can run in NOARCHIVELOG mode without archiving. However, DBWn, LGWR, and CKPT are mandatory background processes - DBWn writes dirty buffers, LGWR writes redo, and CKPT manages checkpoints.

Multiple choice technology databases

Choose the correct hierarchy, from largest to smallest, from this list of logical database structures.

  1. Database, tablespace, extent, segment, block

  2. Database, tablespace, segment, extent, block

  3. Database, segment, tablespace, extent, block

  4. Database, extent, tablespace, segment, block
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The correct hierarchy is Database (largest) → Tablespace → Segment → Extent → Block (smallest). A tablespace contains segments (like tables or indexes), segments are made of extents, and extents are contiguous blocks.

Multiple choice technology databases

What is the minimum number of online redo log files required in a database?

  1. One

  2. Two

  3. Four

  4. Zero
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An Oracle database requires a minimum of two online redo log groups to function. This is because Oracle writes to them in a circular fashion; while one group is being archived or filled, the database must have another group available to continue writing redo entries without halting operations.

Multiple choice technology databases

Which view will contain the name of the database?
  1. V$database
  2. v$controlfile
  3. v$log
  4. V$DB
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

V$DATABASE is the dynamic performance view that contains database name, creation date, and other core database information. Views like V$CONTROLFILE, V$LOG, and V$DB don't exist or don't contain the database name.

Multiple choice technology programming languages

Hibernate is the best solutions for data centric applications that only uses the stored-procedures to implement the business logic in database.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Hibernate is an ORM framework designed for object-oriented domain models, not stored procedure-centric applications. When business logic lives primarily in stored procedures, simpler JDBC-based approaches or tools like MyBatis/iBATIS are often better suited for data access.

Multiple choice technology storage

Data being replicated from site A to site B using disk buffering to create extended distance consistent point in time copies every hour. In the event of a site failure at A, what is the maximum amount of data that will be missing at site B?

  1. 1 Hr

  2. 2 Hr

  3. 3 Hr

  4. 4 Hr
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

With hourly replication from site A to site B, the maximum data loss depends on when failure occurs relative to the replication cycle. If site A fails immediately after a successful replication, site B loses 0 hours of data (just the data from the current uncompleted hour). If site A fails immediately before the next replication, site B loses the entire current hour's data plus potentially the previous hour if replication was delayed. The worst case is approximately 2 hours - the current incomplete hour plus the previous hour's data that hasn't been fully transferred yet.

Multiple choice technology web technology

When configuring session management for a Web container, which property represents the number of cached sessions?

  1. Session Expiry value

  2. Maximum in-memory session count

  3. L2 Cache Integration count

  4. Maximum wait on serial access
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The Maximum in-memory session count property controls how many active sessions the Web container maintains in memory. Sessions beyond this limit may be passivated to disk or secondary storage.