The Relational Model Database:

The Relational Model Database:
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The relational model is the most popular type of database and an extremely powerful tool, not only to  store information, but to access it as well. Relational databases are organized as tables. The beauty of a  table is that the information can be accessed or added without reorganizing the tables. A table can have  many records and each record can have many fields.
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In a relational database model, NULL values can be used for all but which one of the following? (A) To allow duplicate tuples in the table by filling the primary key column(s) with NULL. (B) To avoid confusion with actual legitimate data values like 0 (zero) for integer columns and ‘’ (the empty string) for string columns. (C) To leave columns in a tuple marked as “unknown” when the actual value is unknown. (D) To fill a column in a tuple when that column does not really “exist” for that particular tuple.

Description : In a relational database model, NULL values can be used for all but which one of the following? (A) To allow duplicate tuples in the table by filling the primary key column(s) with NULL. (B) To ... D) To fill a column in a tuple when that column does not really exist for that particular tuple.

Last Answer : (A) To allow duplicate tuples in the table by filling the primary key column(s) with NULL.

Distinguish between network database model and relational database model.

Description : Distinguish between network database model and relational database model. 

Last Answer : Network database model Relational database model Relationship between records is expressed in the form of pointers or links Relationship between records is represented by a relation that contains a key for ... logically in the form of rows and columns. Example:  Example: 

The Network Model Database:

Description : The Network Model Database:

Last Answer : In a network model, the defining feature is that a record is stored with a link to other records – in effect networked. These networks (or sometimes referred to as pointers) can be a variety of different types of information such as node numbers or even a disk address.

The Hierarchical Model Database:

Description : The Hierarchical Model Database:

Last Answer : The hierarchical model database resembles a tree like structure, such as how Microsoft Windows organizes folders and files. In a hierarchical model database, each upward link is nested in order to keep data ... Within this nested file are all of the sales (same types of data) for the day.

The Flat Model Database:

Description : The Flat Model Database:

Last Answer : In a flat model database, there is a two dimensional (flat structure) array of data. For instance, there is one column of information and within this column it is assumed that each data item will be related ... will only be one column and each new row within that one column will be a new zip code.

What are the unary operations in Relational Algebra?

Description : What are the unary operations in Relational Algebra?

Last Answer : PROJECTION and SELECTION.

How does Tuple-oriented relational calculus differ from domain-oriented relational calculus?

Description : How does Tuple-oriented relational calculus differ from domain-oriented relational calculus?

Last Answer : The tuple-oriented calculus uses a tuple variables i.e., variable whose only permitted values are tuples of that relation. E.g. QUEL The domain-oriented calculus has domain variables i.e., variables that range over the underlying domains instead of over relation. E.g. ILL, DEDUCE.

What is Relational Calculus?

Description : What is Relational Calculus?

Last Answer : It is an applied predicate calculus specifically tailored for relational databases proposed by E.F. Codd. E.g. of languages based on it are DSL ALPHA, QUEL.

What is Relational Algebra?

Description : What is Relational Algebra?

Last Answer : It is procedural query language. It consists of a set of operations that take one or two relations as input and produce a new relation.

How is the data structure of System R different from the relational structure? Unlike Relational systems in System R

Description : How is the data structure of System R different from the relational structure? Unlike Relational systems in System R

Last Answer : ∙ Domains are not supported ∙ Enforcement of candidate key uniqueness is optional ∙ Enforcement of entity integrity is optional ∙ Referential integrity is not enforced

RDBMS provides relational operators to manipulate the data. Here, RDBMS refers to (a) Record Database Management System -Technology

Description : RDBMS provides relational operators to manipulate the data. Here, RDBMS refers to (a) Record Database Management System -Technology

Last Answer : (b) RDBMS stands for Relational Database Management System, which provides the operator to manipulate the data stored in the database table.

How are relationship between tables expressed in a relational database?

Description : How are relationship between tables expressed in a relational database?

Last Answer : Tables are the basic building blocks of a relationaldatabase.

What is Relational Database Management System ?

Description : What is Relational Database Management System ?

Last Answer : Database databases are organized in different rows, that is, files are considered only in records, but also in tables with list rows and columns. This type of database is called relational database management system.

Is it true or false that a relational database typically consists of related two dimensional tables?

Description : Is it true or false that a relational database typically consists of related two dimensional tables?

Last Answer : Need answer

In a relational database, this is a data structure that organizes the information about a single topic into rows and columns. 1) Block 2) Record 3) Tuple 4) Table 5) Command line interface

Description : In a relational database, this is a data structure that organizes the information about a single topic into rows and columns. 1) Block 2) Record 3) Tuple 4) Table 5) Command line interface

Last Answer : Answer :4

A relational database management (RDBM) package manages datain morethan one file at once. How does itorganizethese file? As A. tables B. relations C. tuple D. both (a)and (b) E. None of the above

Description : A relational database management (RDBM) package manages datain morethan one file at once. How does itorganizethese file? As A. tables B. relations C. tuple D. both (a)and (b) E. None of the above

Last Answer : both (a)and (b)

Which of the following describes a relational database? 1) It provides a relationship between integers 2) It consists of separate tables or related data 3) It retrieves data related to its queries 4) It provides a relationship between floats

Description : Which of the following describes a relational database? 1) It provides a relationship between integers 2) It consists of separate tables or related data 3) It retrieves data related to its queries 4) It provides a relationship between floats

Last Answer : 2) It consists of separate tables or related data

Which of the following genres does Hadoop produce? a) Distributed file system b) JAX-RS c) Java Message Service d) Relational Database Management System

Description : Which of the following genres does Hadoop produce? a) Distributed file system b) JAX-RS c) Java Message Service d) Relational Database Management System

Last Answer : Distributed file system

Which of the following allows you to create instances of the MySQL database to support your Web sites? a) Amazon Elastic Compute Cloud b) Amazon Simple Queue Service c) Amazon Relational Database Service d) Amazon Simple Storage System

Description : Which of the following allows you to create instances of the MySQL database to support your Web sites? a) Amazon Elastic Compute Cloud b) Amazon Simple Queue Service c) Amazon Relational Database Service d) Amazon Simple Storage System

Last Answer : Amazon Relational Database Service

Which of the following is an edge-storage or content-delivery system that caches data in different physical locations? a) Amazon Relational Database Service b) Amazon SimpleDBc) Amazon Cloudfront d) Amazon Associates Web Services

Description : Which of the following is an edge-storage or content-delivery system that caches data in different physical locations? a) Amazon Relational Database Service b) Amazon SimpleDB c) Amazon Cloudfront d) Amazon Associates Web Services

Last Answer : Amazon Cloudfront

n(log n) is referred to A. A measure of the desired maximal complexity of data mining algorithms B. A database containing volatile data used for the daily operation of an organization C. Relational database management system D. None of these

Description : n(log n) is referred to A. A measure of the desired maximal complexity of data mining algorithms B. A database containing volatile data used for the daily operation of an organization C. Relational database management system D. None of these

Last Answer : A. A measure of the desired maximal complexity of data mining algorithms

Which of the following is not a logical database structure? A) Chain B) Network C) Tree D) Relational

Description : Which of the following is not a logical database structure? A) Chain B) Network C) Tree D) Relational

Last Answer : A) Chain

A top-to-bottom relationship among the items in a database is established by a A) Hierarchical schema B) Network schema C) Relational Schema D) All of the above

Description : A top-to-bottom relationship among the items in a database is established by a A) Hierarchical schema B) Network schema C) Relational Schema D) All of the above

Last Answer : A) Hierarchical schema

A relational database developer refers to a record as (A) a criteria. (B) a relation. (C) a tuple. (D) an attribute.

Description : A relational database developer refers to a record as (A) a criteria. (B) a relation. (C) a tuple. (D) an attribute.

Last Answer : C) a tuple

Which of the following is not a type of Database Management System? (A) Hierarchical (B) Network (C) Relational (D) Sequential

Description : Which of the following is not a type of Database Management System? (A) Hierarchical (B) Network (C) Relational (D) Sequential 

Last Answer : (D) Sequential

Which of the following statements concerning Object-Oriented databases is FALSE? (A) Objects in an object-oriented database contain not only data but also methods for processing the data. (B) Object-oriented databases store computational instructions in the same place as the data. (C) Object-oriented databases are more adapt at handling structures (analytical) data than relational databases. (D) Object-oriented databases store more types of data than relational databases and access that data faster.

Description : Which of the following statements concerning Object-Oriented databases is FALSE? (A) Objects in an object-oriented database contain not only data but also methods for processing the data. (B ... Object-oriented databases store more types of data than relational databases and access that data faster.

Last Answer : (C) Object-oriented databases are more adapt at handling structures (analytical) data than relational databases.

Relational database schema normalization is NOT for: (A) reducing the number of joins required to satisfy a query. (B) eliminating uncontrolled redundancy of data stored in the database. (C) eliminating number of anomalies that could otherwise occur with inserts and deletes. (D) ensuring that functional dependencies are enforced.

Description : Relational database schema normalization is NOT for: (A) reducing the number of joins required to satisfy a query. (B) eliminating uncontrolled redundancy of data stored in the database. (C) ... could otherwise occur with inserts and deletes. (D) ensuring that functional dependencies are enforced. 

Last Answer : reducing the number of joins required to satisfy a query.

The database in which records are organised in a tree-like structure is (1) Network database (2) Hierarchical database (3) Relational database (4) Object-oriented database

Description : The database in which records are organised in a tree-like structure is (1) Network database (2) Hierarchical database (3) Relational database (4) Object-oriented database

Last Answer : Hierarchical database

Expansion of RDBMS is (1) Repairable Database Management System (2) Relational Database Management System (3) Relational Database Memory System (4) Recurring Database Memory System

Description : Expansion of RDBMS is (1) Repairable Database Management System (2) Relational Database Management System (3) Relational Database Memory System (4) Recurring Database Memory System 

Last Answer : Relational Database Management System

How does one manage Oracle database users? (for DBA

Description : How does one manage Oracle database users? (for DBA

Last Answer : Oracle user accounts can be locked, unlocked, forced to choose new passwords, etc. For example, all accounts except SYS and SYSTEM will be locked after creating an Oracle9iDB database using the DB ... locked users account ALTER USER scott PASSWORD EXPIRE; -- Force user to choose a new password

How does one manage Oracle database users? (for DBA

Description : How does one manage Oracle database users? (for DBA

Last Answer : Oracle user accounts can be locked, unlocked, forced to choose new passwords, etc. For example, all accounts except SYS and SYSTEM will be locked after creating an Oracle9iDB database using the ... from SYS.V$BH log buffer spaces Increase LOG_BUFFER parameter or move log files to faster disks

How does one backup a database using the export utility? (for DBA

Description : How does one backup a database using the export utility? (for DBA

Last Answer : Oracle exports are "logical" database backups (not physical) as they extract data and logical definitions from the database into a file. Other backup strategies normally back-up the physical data ... exports include more information about the database in the export file than user level exports.

What strategies are available for backing-up an Oracle database? (for DBA

Description : What strategies are available for backing-up an Oracle database? (for DBA

Last Answer : The following methods are valid for backing-up an Oracle database: Export/Import - Exports are "logical" database backups in that they extract logical definitions and data from the database to a file. ... , etc. If your database is in ARCGIVELOG mode, you also need to backup archived log files.

Why and when should I backup my database? (for DBA

Description : Why and when should I backup my database? (for DBA

Last Answer : Backup and recovery is one of the most important aspects of a DBAs job. If you lose your company's data, you could very well lose your job. Hardware and software can always be ... things that will get you. Most failed recoveries are a result of organizational errors and miscommunications.

What are the roles and user accounts created automatically with the database?

Description : What are the roles and user accounts created automatically with the database?

Last Answer : DBA - role Contains all database system privileges. SYS user account - The DBA role will be assigned to this account. All of the base tables and views for the database's dictionary ... administrative information and internal tables and views used by oracle tools are created using this username.

What are the responsibilities of a Database Administrator ?

Description : What are the responsibilities of a Database Administrator ?

Last Answer : Installing and upgrading the Oracle Server and application tools. Allocating system storage and planning future storage requirements for the database system. Managing primary database structures ... tape Backing up and restoring the database. Contacting Oracle Corporation for technical support.

How does one create a standby database? (for DBA)

Description : How does one create a standby database? (for DBA)

Last Answer : While your production database is running, take an (image copy) backup and restore it on duplicate hardware. Note that an export will not work!!! On your standby database, issue ... the standby database, stop the recovery process and activate it: ALTER DATABASE ACTIVATE STANDBY DATABASE;

Name two files used for network connection to a database.

Description : Name two files used for network connection to a database.

Last Answer : TNSNAMES.ORA and SQLNET.ORA

When creating a user, what permissions must you grant to allow them to connect to the database?

Description : When creating a user, what permissions must you grant to allow them to connect to the database?

Last Answer : Grant the CONNECT to the user.

Name a tablespace automatically created when you create a database.

Description : Name a tablespace automatically created when you create a database.

Last Answer : The SYSTEM tablespace.

How would you determine the time zone under which a database was operating?

Description : How would you determine the time zone under which a database was operating?

Last Answer : select DBTIMEZONE from dual;

Where would you look for errors from the database engine?

Description : Where would you look for errors from the database engine?

Last Answer : In the alert log.

You have just had to restore from backup and do not have any control files. How would you go about bringing up this database?

Description : You have just had to restore from backup and do not have any control files. How would you go about bringing up this database?

Last Answer : I would create a text based backup control file, stipulating where on disk all the data files where and then issue the recover command with the using backup control file clause.

What is network database link?

Description : What is network database link?

Last Answer : Network database link is created and managed by a network domain service. A network database link can be used when any user of any database in the network specifies a global object name in a SQL statement or object definition.

What is public database link?

Description : What is public database link?

Last Answer : Public database link is created for the special user group PUBLIC. A public database link can be used when any user in the associated database specifies a global object name in a SQL statement or object definition.

What is private database link?

Description : What is private database link?

Last Answer : Private database link is created on behalf of a specific user. A private database link can be used only when the owner of the link specifies a global object name in a SQL statement or in the definition of the owner's views or procedures.

What are the types of database links?

Description : What are the types of database links?

Last Answer : Private database link, public database link & network database link.

What is Database Link ?

Description : What is Database Link ?

Last Answer : A database link is a named object that describes a "path" from one database to another.