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.