Explain the features, benefits and limitations of a relational database
A relational database stores data in tables . Each table is made up of: records (row = record = tuple = instance) each row stores one complete item fields…
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A relational database stores data in tables.
Each table is made up of:
records (row = record = tuple = instance)
each row stores one complete item
fields (column = attribute = field = feature)
each column stores one attribute of that item
Example:
StudentID
Name
Class
101
Alice
11A
102
Ben
11B
Main features of a relational database
Table-based structure
data is organized into tables
each table represents one entity, such as Students, Teachers, or Orders
Primary key
a field that uniquely identifies each record in a table
example:
StudentID
Foreign key
a field in one table that links to the primary key in another table
this creates a relationship between tables
Relationships
tables can be linked together
common relationships (cardinality):
one-to-one
one-to-many
many-to-many
Structured query language (SQL)
used to create, search, update, and delete data
example operations:
SELECT
INSERT
UPDATE
DELETE
Data integrity
validation rules and relationships help keep data accurate and consistent
example:
you cannot assign an order to a customer that does not exist if referential integrity is enforced
Referential integrity ensures that every foreign key value matches an existing primary key value in the related table.
Reduced redundancy through normalization
data is split into related tables to avoid unnecessary duplication
this improves consistency
Benefits of a relational database
Reduced duplication
the same data does not need to be repeated in multiple places
this saves storage and reduces inconsistency
Improved consistency
if one value changes, it can be updated once in one table instead of many times
Better data integrity
keys, validation, and constraints help prevent invalid data
Efficient querying
SQL makes it easy to search, sort, filter, and combine data from multiple tables
Scalability for structured data
relational databases work well when data is clearly structured and relationships are important
Security and access control
users can be given different permissions for viewing or editing data
Multi-user access
many users can work with the database at the same time
transaction control helps maintain correctness
Limitations of a relational database
Complex design
building a good relational database requires careful planning
tables, keys, and relationships must be designed properly
Less suitable for unstructured data
relational databases are best for structured data
they are less suitable for documents, media-heavy data, or highly variable data structures
Can become complex with many relationships
large systems may need many linked tables
complex joins can be harder to understand and maintain
Performance overhead
highly complex queries across many tables may be slower
Schema changes can be disruptive
changing table structures after deployment can be difficult
Many-to-many relationships require extra tables
an additional linking table is usually needed
this increases design complexity
Simple example of a relationship
Students table
StudentID
Name
101
Alice
102
Ben
Classes table
ClassID
ClassName
C1
Biology
C2
Chemistry
Enrollments table
StudentID
ClassID
101
C1
101
C2
102
C1
Here:
StudentID and ClassID in Enrollments are foreign keys