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| Database Modeling Building Blocks |
1. Define data and information
Data: Data is a term applied to organized information.
Information: Information is data that is stored in a database, processed by programs, or even transmitted over a network such as the Internet (between multiple users).
2. What is data integrity?
The integrity of data is the validity of data. A set of rules in a database Model, ensuring that data is not lost within the database and that data is only destroyed when it should be.
3. What is table?
A table is an entity that is divided into fields and records, used to store information in processing.
4. What is datatypes?
A datatype restricts values in fields. It comprise the forms data can take such as numbers, dates, strings and others.
5. Describe the classification of data types?
There are many different types of data types. It can be divided into three separate sections.
(1) Simple data types
(a) Strings
(i) Fixed-length strings (CHAR)
(ii) Variable-length strings (VARCHAR)
(b) Numbers
(i) Integers
(ii) Fixed-length decimals
(iii) Floating points
(c) Dates and times
(2) Complex data types
(a) Binary objects
(b) Reference pointers
(c) Collection arrays
(d) User-defined types
(3) Specialized data types
6.What is constraints in database?
Constraints means to restricts, or apply rules both within and between tables.
There are five Constraint given below.
i. NOT NULL
ii. Validation check
iii. Key
a. Primary key
b. Foreign key
c. Unique key
7. What is Normalization?
Normalization can be described as being one of introduction of granularity, removal of duplication, or minimizing of redundancy, or simply the introduction of tables, all of which place data into a better organized state.
8. Describe the benefits of Normalization.
i. Removal of duplication
ii. Minimizing redundancy
iii. Better organized data
9. Define primary key, unique key and foreign key.
Primary Key: A primary key is used to uniquely identify a record in a table.
It allows
• NOT NULL
• Not Duplicate values
• Only one PK in a table
• Automatically create an index in the table
Unique key: A key created on a field containing only unique values throughout an entire table.
It allows
• NULL value
• Not duplicate
•More than one UK in a table
Foreign Key: A foreign key is the copy of a primary key created into child tables to form the opposite side of the link in an inter-table relationship-establishing a relational database relation.
It allows
• Null value
• Duplicate
• More than one FK in a table
10. Deference between Primary key and Unique Key.
The basic deference’s between Primary key and Unique Key are
Primary key allowed
• NOT NULL and
• Only one PK in a table
Unique key allowed
• NULL value and
• More than one UK in a table
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