Oracle Database: Lecture – 01

Question: What is data?

Answer: Every organization has some information needs. A library keeps a list of members, books, due dates, and fines. A company needs to save information about employees, departments, and salaries. These pieces of information are called data.

Question: What is database?

Answer: A database is an organized collection of information.

 

Question: What do we need to manage a database?

Answer: To manage databases, we need a database management system (DBMS).

 

Question: What is DBMS?

Answer: A DBMS is a program that stores, retrieves, and modifies data in databases on request.

 

Question: What are four types of database?

Answer:

• Hierarchical
• Network
• Relational and
• Object relational (Most recently)

 

Question: What does RM consist?

Answer:

• Collection of objects or relations
• Set of operators to act on the relations
• Data integrity for accuracy and consistency

 

Question: What are components of RM?

Answer:

• Collections of objects or relations that store the data
• A set of operators that can act on the relations to produce other relations
• Data integrity for accuracy and consistency

 

Question: What is relational database?

Answer: A relational database is a collection of relations or two-dimensional tables. A relational database uses relations or two-dimensional tables to store information.

 

Question: What are the purposes of model?

Answer:

• Communicate
• Categorize
• Describe
• Specify
• Investigate
• Evolve
• Analyze
• Imitate

 

Question: What is ERM?

Answer: An entity relationship model is an illustration of various entities in a business and the relationships among them. An ER model is derived from business specifications or narratives and built during the analysis phase of the system development life cycle.

 

Question: What are the benefits of ERM?

Answer:

• Documents information for the organization in a clear, precise format
• Provides a clear picture of the scope of the information requirement
• Provides an easily understood pictorial map for database design
• Offers an effective framework for integrating multiple applications

 

Question: What are conventions of ERM?

Answer:

• Entity
  • Singular, unique entity name
  • Entity name in uppercase
  • Soft Box
  • Optional synonym names in uppercase within parentheses: ()
• Attribute
  • Singular name in lowercase
  • Asterisk (*) tag for mandatory attributes
  • Letter “o” tag for optional attributes

 

Question: What is primary key and foreign key?

Answer:

• A primary key is a column that refers each row of data in a table is uniquely identified by primary key.
• A foreign key is a column (or a set of columns) that refers to a primary key in the same table or another table.

 

Question: What are guidelines of primary key and foreign key?

Answer:

• We cannot use duplicate values in a primary key.
• Primary keys generally cannot to change.
• Foreign keys are based on data values and are purely logical (not physical) pointers.
• A foreign key value must match an existing primary key value or unique key value, or else it must be null.
• A foreign key must reference either a primary key or a unique key column.

 

Question: What is table?

Answer: A relational database can contain one or many tables. A table is the basic storage structure of an RDBMS. A table holds all the data necessary about something in the real world, such as employees, invoices, or customers.

 

Question: Discuss Relational Database properties?

Answer:

• A relational database can be accessed and modified by executing structured query language (SQL) statements.
• A relational database contains a collection of table with no physical pointers.
• A relational database uses a set of operators.

 

Question: Define / Discuss SQL statement?

Answer:

• Data manipulation language (DML): Retrieves data from the database, enters new rows, changes existing rows, and removes unwanted rows from tables in the database, respectively. Collectively known as data manipulation language.
  • SELECT
  • INSERT
  • UPDATE
  • DELETE
  • MERGE
• Data definition language (DDL): Sets up, changes, and removes data structures from tables. Collectively known as data definition language.
  • CREATE
  • ALTER
  • DROP
  • RENAME
  • TRUNCATE
  • COMMENT
• Data control language (DCL): Gives or removes access rights to both the Oracle database and the structures within it.
  • GRANT
  • REVOKE
• Transaction control: Manages the changes made by DML statements. Changes to the data can be grouped together into transactions.
  • COMMIT
  • ROLLBACK
  • SAVEPOINT

 

Question: What is SQL?

Answer: SQL is the language that used to communicate with the server to access, manipulate, and control data.

 

Note:

• E.F. Codd proposed Relational Model of for database in 1970.
• RDBMS means Relational Database management system.