What is DBMS:
DBMS (Database Management System) is software that manages and organize data in a database, including tools for creating, storing, retrieving, and updating data while ensuring consistency, integrity, and security.
What is RDBMS:
RDBMS stands for Relational Database Management System. store the data into the collection of tables, which is related by common fields between the columns of the table. It also provides relational operators to manipulate the data stored into the tables.
Examples of DBMS and RDBMS include Microsoft SQL Server, Oracle Database, MySQL, and PostgreSQL.
Types of Relationships in a Database:
In a database, relationships describe how tables are connected to each other based on common attributes or keys.
Types of relationships include one-to-one, one-to-many, and many-to-many.
E-R Model:
Graphical representation for designing database schemas, using entities, attributes, and relationships to describe data. Example: Customer entity with name, address, and phone number attributes, related to Order entity through one-to-many relationship.
Data Integrity Constraints:
Data integrity constraints are rules that ensure the accuracy and consistency of data in a database. They prevent invalid data from being entered or changes that would violate the integrity of the data. Examples include primary keys, foreign keys, unique constraints, and check constraints.
Database Keys:
- Primary Key: A unique identifier for a table that ensures data integrity and efficient querying. Example: User ID in a User table.
- Foreign Key: A column that references a primary key in another table, creating a relationship. Example: Customer ID in an Order table referencing the Customer table’s primary key.
- Super Key: A set of one or more columns that uniquely identifies each row, containing more attributes than necessary. Example: Customer ID and email address in a Customer table.
- Candidate Key: A unique key selected from the set of super keys that can identify a row in a table. Example: Student ID and email address in a Student table.
- Alternate Key: A candidate key that is not selected as the primary key. Example: Student ID in a Student table, if the email address is selected as the primary key.
Entity and Attribute:
An entity represents a real-world object or concept, such as a person or a product.
An attribute describes a characteristic or property of an entity.
Example: A Customer entity has attributes such as name, address, and phone number.
Tuple: A tuple is a row in a table that represents a single instance of the data.
Example: In a Customer table, a single row (tuple) might contain attributes such as name, address, and phone number.
Normalisation:
Normalisation is the process of organizing data in a database to minimize redundancy and dependency. It involves dividing large tables into smaller, more specialized tables, and establishing relationships between them.
Example: In a normalized database, customer information might be stored in a separate table from order information, with a foreign key establishing a relationship between the two.
Generalization:
Generalization is the process of creating a more general entity from a set of more specialized entities. It involves identifying common attributes and relationships between entities and combining them into a single entity. Example: A Customer and Employee entity might be generalized into a Person entity, with common attributes such as name and address.
Relational Algebra Operations – Union and Intersection:
• Union combines two tables into one, removing duplicates.
• Intersection returns only the rows that appear in both tables.
Example: Table1 UNION Table2, Table1 INTERSECT Table2
Logical Data Independence:
Logical Data Independence is the ability to change a database’s structure without affecting applications that use the data.
Sequential file organization:
Sequential file organization stores records in a sequential order based on a particular key field. The records can only be accessed in the order they are stored, making it efficient for tasks that require processing all records in a specific order, but inefficient for tasks that require accessing individual records randomly.
Function dependency:
Function dependency is a relationship between two attributes in a database where the value of one attribute determines the value of another attribute. It helps to ensure data consistency and eliminate redundancy in the database.
Indexed File organization:
method of organizing data in a database where an index is created to improve the efficiency of searching and retrieving data. The index contains a list of keys and their corresponding record addresses, allowing for quick access to the desired data. This method is commonly used for large databases where frequent data retrieval is necessary.
ACID properties:
- Atomicity: All actions in a transaction must either take place at once or not at all.
- Consistency: The database must remain consistent before and after a transaction.
- Isolation: Multiple concurrent transactions should not interfere with each other.
- Durability: Changes made to the database by a transaction should persist even if there are system failures.
Emerging Trends in Database Technologies:
- Cloud databases: Cloud-based databases are becoming increasingly popular as they provide scalability, flexibility, and cost-effectiveness. Cloud databases allow users to easily store and access data from anywhere with an internet connection.
- NoSQL databases: NoSQL databases are gaining popularity because they are more flexible than traditional SQL databases. NoSQL databases allow users to store and retrieve unstructured data, which is especially useful for big data applications.
- In-memory databases: In-memory databases are becoming more prevalent as they offer faster performance than traditional disk-based databases. In-memory databases store data in RAM, which reduces the need for disk I/O operations.
- Graph databases: Graph databases are designed for applications that require complex data relationships, such as social networks or recommendation engines. Graph databases use graph structures to represent and store data, making it easier to query complex relationships.
- Blockchain databases: Blockchain databases are being explored for their potential in creating decentralized and secure databases. Blockchain databases use cryptography and consensus algorithms to ensure the integrity and security of data.
Introduction to SQL:
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What is DBMS: DBMS (Database Management System) is software that manages and organize data in a database, including tools for creating, storing, retrieving, and updating data while ensuring consistency, integrity, and security. What is RDBMS: RDBMS stands for Relational Database Management System. store the data into the collection of tables, which is related by commonContinue reading “A Comprehensive Introduction to Database Management Systems.”
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