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.

E-R Model ConceptsBackup and RecoverySQL Server UpgradesJDBC and ODBCBig Data CharacteristicsData VirtualizationOracle Database

Database Management Systems Questions

Multiple choice technology

Attribute(of dimensions) with which data type will be visible in reporting?

  1. TEXT

  2. DECIMAL

  3. DATE

  4. NUMBER
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Dimension attributes with TEXT data type are designed to store descriptive labels and names that appear directly in reports and UIs. Numeric types (DECIMAL, NUMBER) and DATE are used for filtering, sorting, and calculations rather than display. Reporting tools use TEXT attributes to show human-readable dimension member names and descriptions in rows, columns, and filters.

Multiple choice technology programming languages

What are the types of JDBC Driver Models?

  1. Two tier model

  2. Three tier model

  3. Both a & b

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

JDBC supports both two-tier and three-tier models. Two-tier has the application directly connected to the database, while three-tier introduces middleware between application and database for better management.

Multiple choice technology programming languages

select all the valid values for collation

  1. sqlupper

  2. sqlvarchar

  3. exact

  4. mvr

  5. truncate
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation

Valid collation values in Cache ObjectScript are sqlupper (case-insensitive comparison), exact (case-sensitive exact match), and mvr (numeric range). Sqlvarchar and truncate are not valid collation values in the system. Collation determines how string comparison and sorting operations are performed.

Multiple choice technology databases

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

A check constraint restricts the values that can be entered into a column. It must be defined as a fixed condition during table creation or alteration. Check constraints cannot reference external lookup tables, pseudo-columns like SYSDATE, or enforce non-null values directly without specific syntax.

Multiple choice technology databases

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

The LOCK transaction control prevents concurrent users from updating the same data simultaneously. Unlike commit (save changes), rollback (undo changes), or savepoint (mark a rollback point), lock actually restricts access to prevent conflicts during multi-user scenarios. It ensures data consistency by serializing access to the data.

Multiple choice technology databases

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

The MONTHS_BETWEEN function calculates the number of months between two dates, returning a numeric value rather than a DATE datatype. Functions like NEW_TIME, LAST_DAY, and ADD_MONTHS all perform date calculations and return a DATE datatype, making the numeric function the correct exception.

Multiple choice technology mainframe

Expansion for DBRM

  1. Database Rate Modifier

  2. Database Rate Module

  3. Database Request Module

  4. Database Request Modifier
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

DBRM stands for Database Request Module, which is a compiled SQL program structure in IBM DB2. It contains the optimized access path for SQL statements and is created during the precompilation process. The DBRM is bound to a plan or package for execution in the DB2 environment.

Multiple choice technology mainframe

Requirement is to read all the distinct values of following fields from a table called 'IDENTIFICATION-TABLE'. Fields need to be extracted are 1) IDENT-ID 2) IDENT-NAME 3) IDENT-AGE Super to be used for this requirement is SUPER-ID-NAME-AGE (combination of above fields). Which statement will be used to read the data efficiently from IDENTIFICATION-TABLE?

  1. Read Statement

  2. Find Statement

  3. Histogram Statement

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

The HISTOGRAM statement in Natural/ADABAS is specifically designed for efficiently retrieving distinct values (unique occurrences) from specified fields, which is exactly what this requirement needs.

Multiple choice technology mainframe

Data in the database ------------------------------- IDENT-ID IDENT-NAME IDENT-AGE 1234 AAAA 12 1234 AAAA 12 3456 CCCC 14 6879 DDDD 17 7625 EEEE 21 HISTOGRAM IDENTIFICATION-TABLE BY SUPER-ID-NAME-AGE STARTING FROM '1234' WRITE IDENT-ID IDENT-NAME IDENT-AGE END-HISTOGRAM How many records will be displayed in the output?

  1. No records will be displayed

  2. 5

  3. 4

  4. 3
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A Natural HISTOGRAM statement reads a descriptor, returning one loop cycle per unique value. Starting from '1234', there are four distinct descriptor values present: '1234 AAAA 12', '3456 CCCC 14', '6879 DDDD 17', and '7625 EEEE 21'. The duplicate '1234' record does not produce an extra iteration.

Multiple choice technology mainframe

Data in the database-------------------------------IDENT-ID IDENT-NAME IDENT-AGE IDENT-SEX1234 AAAA 12 M1234 AAAA 12 F3456 CCCC 14 F6879 DDDD 17 M7625 EEEE 21 FHISTOGRAM IDENTIFICATION-TABLE BY SUPER-ID-NAME-AGE STARTING FROM '1234' WRITE IDENT-ID IDENT-NAME IDENT-AGE IDENT-SEXEND-HISTOGRAMWhat will be the output of the job?

  1. 4 records will be displayed

  2. 5 records will be displayed

  3. Job will fail abnormally

  4. Job will run successfully but will not show any records
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The HISTOGRAM uses a superdescriptor SUPER-ID-NAME-AGE. In the data, IDENT-ID 1234 appears twice with different values for NAME/SEX (AAAA/M vs AAAA/F). This creates a duplicate key situation in the superdescriptor, which violates Adabas uniqueness constraints. The job will fail abnormally due to this constraint violation.

Multiple choice technology mainframe

Data in the database ------------------------------- IDENT-ID IDENT-NAME IDENT-AGE 1234 AAAA 12 2345 BBBB 23 3456 CCCC 14 6879 DDDD 17 7625 EEEE 21 HISTOGRAM IDENTIFICATION-TABLE BY SUPER-ID-NAME-AGE STARTING FROM '1235' WRITE IDENT-ID IDENT-NAME IDENT-AGE END-HISTOGRAM What records will be displayed in the output?

  1. No records will be displayed

  2. 2nd to 5th record will be displayed

  3. 2nd record alone will be displayed

  4. All records will be displayed
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

HISTOGRAM with SUPER-ID-NAME-AGE starting from '1235' will display all records where the superdescriptor key is greater than or equal to '1235'. The first record (ID 1234) is excluded. Records 2-5 (IDs 2345, 3456, 6879, 7625) all have keys >= 1235, so they are displayed. Option B is correct.

Multiple choice technology mainframe

RRDS = Relative Record Data Set

  1. True

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

RRDS (Relative Record Data Set) is a VSAM file type where records are accessed by their relative record number (position), allowing direct access without requiring a key field.

Multiple choice technology databases

Which datatype stores data outside Oracle Database?

  1. UROWID

  2. BLOB

  3. NCLOB

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

BFILE is a unique Oracle datatype that stores a file pointer to data located outside the database in the operating system filesystem. Unlike BLOB and CLOB types which store data within the database, BFILE only maintains a reference to external files. UROWID is for rowids, NCLOB stores character large objects within the database.

Multiple choice technology databases

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

Unique key constraints allow NULL values, whereas primary key constraints strictly forbid NULL values in their columns. Additionally, a pre-existing non-unique index can be used to enforce a primary key constraint if created beforehand. This makes the marked true options correct and the other choices false.