Database about data and programming lofe.pptx
- 1. Building a Multitable Relational Database Ovezov Atanazar
- 2. What is a Relational Database? β’ A relational database is a type of database that stores data in tables, where each table represents a specific entity. The rows in these tables contain individual records, and the columns define the attributes of those records. Relational databases are based on mathematical principles and use Structured Query Language (SQL) to manage and query data.
- 3. Why Multitable Design? β’ Multitable database design is essential for maintaining data integrity and avoiding redundancy. For instance, instead of storing a student's personal information multiple times across different tables, a multitable approach links student records to other data using unique identifiers. This approach makes the database more organized, easier to maintain, and more efficient to query.
- 4. Key Components of a Relational Database Relational databases consist of several critical components: β’Tables: These are the primary structures where data is stored. β’Primary Keys: Unique identifiers for each row in a table. β’Foreign Keys: Attributes that establish a relationship between tables, ensuring data consistency and integrity.
- 5. Relational Algebra β’ Relational algebra provides the theoretical foundation for operations in a relational database. It defines a set of operations like selection, projection, and joining that allow us to manipulate and retrieve data efficiently. For example, the JOIN operation combines data from two or more tables based on related columns, enabling complex queries across multiple tables.
- 6. Data Normalization Normalization is a process that organizes data to reduce redundancy and improve efficiency. It involves dividing a database into smaller tables and defining relationships between them. The three main normal forms include: β’First Normal Form (1NF): Ensures that each column contains atomic values. β’Second Normal Form (2NF): Eliminates partial dependencies on the primary key. β’Third Normal Form (3NF): Removes transitive dependencies.
- 7. Example of Normalization Imagine a table where student data, course names, and instructors are stored together. This structure may lead to repeated information, such as the same course name being listed for multiple students. By normalizing the data: β’ 1. The Student Table contains only student-specific information. β’ 2. The Course Table holds course-specific details. β’ 3. A linking Enrollment Table connects students to courses, reducing redundancy.
- 8. Requirements Analysis The first step in designing a multitable relational database is understanding the requirements of the system. This involves identifying the type of data to be stored, the relationships between different types of data, and the types of queries users will perform. For example, a library system must track books, members, and loans while enabling users to search for available books.
- 9. Conceptual Design β’ The conceptual design phase uses tools like Entity-Relationship (ER) diagrams to visualize the data model. Entities represent real-world objects, such as students or books, and relationships define how these entities interact. For example, an ER diagram for a university database would show entities like Students, Courses, and Enrollments, with lines connecting them to illustrate relationships.
- 10. Sample ER Diagram A sample ER diagram for a university database includes: β’Entities: Students, Courses, Instructors. β’Attributes: Each entity's unique details, such as StudentID or CourseName. β’Relationships: How entities are connected, such as "Students enroll in Courses."
- 11. Logical Design β’ After creating the conceptual model, the next step is to translate it into a relational schema. Each entity becomes a table, with attributes as columns. Relationships are implemented using foreign keys. For example, the Students table might have columns for StudentID, Name, and Major, while the Enrollments table links students to courses using StudentID and CourseID.
- 12. Schema Design Example In a library system: β’Books Table: Stores information like BookID, Title, and Author. β’Members Table: Contains MemberID, Name, and Address. β’Loans Table: Links Members to Books using MemberID and BookID, with additional details like LoanDate and ReturnDate.
- 13. Importance of Primary and Foreign Keys β’ Primary keys ensure that every record in a table is unique, preventing duplicate entries. Foreign keys enforce relationships between tables, ensuring that related data remains consistent. For example, if a student record is deleted, foreign key constraints can prevent the removal of associated enrollment records.
- 14. Creating Tables SQL commands are used to create tables in a database. For example: CREATE TABLE Students ( StudentID INT PRIMARY KEY, Name VARCHAR(100), Major VARCHAR(50) ); This command creates a Students table with columns for student information.
- 15. Populating Tables Once tables are created, they can be populated with data using INSERT INTO statements. INSERT INTO Students (StudentID, Name, Major) VALUES (1, 'Alice', 'Computer Science');
- 16. Querying Multitable Databases To retrieve data from multiple tables, JOIN operations are used. SELECT Students.Name, Courses.Title FROM Students JOIN Enrollment ON Students.StudentID = Enrollment.StudentID JOIN Courses ON Enrollment.CourseID = Courses.CourseID; This query lists students along with the courses they are enrolled in.
- 17. Data Integrity and Constraints β’ Maintaining data integrity is crucial in database design. Constraints like NOT NULL, UNIQUE, and FOREIGN KEY ensure that data remains valid. For example, a NOT NULL constraint on the Name column prevents adding a student without a name.
- 18. Performance Optimization Indexing is a technique used to speed up data retrieval. For example, creating an index on the StudentID column allows faster searches in the Students table. Additionally, query optimization ensures that SQL statements are written efficiently.
- 19. Practical Example - Library Management System A library database consists of: β’ Books Table for storing book information. β’ Members Table for member details. β’ Loans Table for tracking which books are borrowed by which members.
- 20. Global Applications of Relational Databases Relational databases are used worldwide in industries like e-commerce, banking, healthcare, and education. They enable businesses to store and analyze data efficiently, supporting operations like customer management, order processing, and financial tracking.
- 21. Challenges in Multitable Design β’ Designing multitable databases can be challenging. Issues include ensuring data consistency, managing complex relationships, and optimizing query performance. Addressing these challenges requires a thorough understanding of database principles and careful planning.
- 22. Case Study A university database is designed to manage students, courses, and instructors. Tables like Students, Courses, and Enrollments are linked to enable functionalities like listing students in a course or finding courses taught by an instructor.
- 23. Summary β’ Multitable relational databases provide a robust framework for organizing and managing data. By normalizing data, defining relationships, and ensuring data integrity, these databases support efficient and scalable applications.
- 24. Conclusion Building a multitable relational database is a systematic process involving design, implementation, and optimization. When done correctly, it creates a reliable and efficient system for managing complex data relationships.
- 25. THANK YOU!