review of theory of database
TRANSCRIPT
*Property of STI K0019
Review of Theory of Databases
Review of Database Concepts
*Property of STI K0019
Review of Database Concepts
What is a Database? A database is a collection of logically related data.
Example: Personal information such as name, address, birthday and gender
What is a Schema? A schema or a database schema is the over-all design of a
database.
What is a Database System? A database system is an automated system that enables users
to define, create, maintain and control access to the database.
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Review of Database Concepts
What are the components of the DBMS Environment?
Data Hardware Software End Users Procedure
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Review of Database Concepts
What are the different facilities that DBMS provide?
Users can define the database through a Data Definition Language (DDL).
Users can manipulate data through a Data Manipulation Language (DML).
DBMS can provide security system. DBMS can provide an integrity system. DBMS can provide a concurrency control system. DBMS can provide a recovery control system.
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Review of Database Concepts
What are the different entity relationships? One-to-One
Table A Table B
A1
A2
A3
A4
B1
B2
B3
B4
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Review of Database Concepts
What are the different entity relationships? One-to-Many
Table A Table B
A1
A2
A3
B1
B2
B3
B4
B5
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Review of Database Concepts
What are the different entity relationships? Many-to-One
Table BTable A
B1
B2
B3
A1
A2
A3
A4
A5
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Review of Database Concepts
What are the different entity relationships? Many-to-Many
Table A Table B
A1
A2
A3
A4
B1
B2
B3
B4
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Review of Database Concepts
What is relational database? A relational database is divided into logical units
called table which is composed of rows and columns of data.
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Review of Database Concepts
What is a relation? A relation is composed of rows and columns of data.
What is an attribute? In relational database, the table columns correspond to
attributes. What is a domain?
A domain refers to a set of valid atomic values for a given attribute.
What is a primary key? A primary key refers to an attribute or field that serves as
a unique identifier for a particular record within a relation.
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Review of Database Concepts
What is SQL? Structured Query Language (SQL) is the standard
language used to define, query, update and maintain relational databases.
Main categories of SQL commands are as follows: Data Definition Language (DDL) Data Manipulation Language (DML) Data Query Language (DQL) Data Control Language (DCL) Transactional control commands
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Review of Database Concepts
What is Data Definition Language (DDL)? The DDL allows the user to create and restructure database
objects. Some of the most fundamental DDL commands are:
CREATE TABLE ALTER TABLE DROP TABLE CREATE INDEX ALTER INDEX DROP INDEX CREATE VIEW DROP VIEW
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Review of Database Concepts
What is Data Control Language (DML)? DML allows the user to manipulate data within objects of
a relational database. The three basic DML commands are
INSERT UPDATE DELETE
What is Data Query Language (DQL)? DQL allows the user to select a data or a group of data. The base command is SELECT
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Review of Database Concepts
What is Data Control Language (DCL)?
The DCL allows the user to create objects related to user access and also control the distribution of privileges among users.
Some data control commands are as follows:
ALTER PASSWORD GRANT REVOKE CREATE SYNONYM
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Review of Database Concepts
What is Transactional Control Commands (TCC)? The TCC allow the user to manage database
transactions. Some commands are as follows:
COMMIT ROLLBACK SAVEPOINT SET TRANSACTION
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Review of Database Concepts
What is Integrity Constraint? Integrity constraints are used to ensure accuracy and
consistency of data in a relational database.
What are the types of integrity constraints? Primary key Constraints Unique Constraints Foreign Key Constraints Not Null Constraints Check Constraints
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Review of Database Concepts
What is normalization?
Normalization is a process of reducing data redundancy in a database.
The different levels of normal forms:
First Normal Form (1NF) Second Normal Form (2NF) Third Normal Form (3NF)
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Review of Database Concepts
What are the advantages of normalization?
Better overall database organization Reduction of redundant data Data consistency within the database Flexible database design Efficient database security handling Enforces concept of referential integrity