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.

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