डेटाबेस प्रबंधन प्रणाली में कुंजी प्रकार

Types of DBMS Keys

• Super Key: A set of one or more attributes that uniquely identifies a tuple in a relation.
• Candidate Key: A minimal super key, i.e., a set of attributes that uniquely identifies a tuple and cannot be further reduced.
• Primary Key: A chosen candidate key that uniquely identifies a tuple in a relation.
• Alternate Key: A candidate key that is not chosen as the primary key.
• Composite Key: A primary key composed of multiple attributes.
• Foreign Key: An attribute in a relation that refers to the primary key of another relation.

Properties of DBMS Keys

• Uniqueness: Keys must uniquely identify each tuple in a relation.
• Minimality: Candidate keys must be minimal, i.e., they cannot be further reduced.
• Irreducibility: Composite keys must be irreducible, i.e., they cannot be broken down into smaller keys.

Functions of DBMS Keys

• Uniquely identify tuples: Keys ensure that each tuple in a relation is unique.
• Enforce data integrity: Keys help maintain data consistency and accuracy by preventing duplicate or inconsistent data.
• Establish relationships: Foreign keys establish relationships between relations.
• Improve query performance: Keys can improve query performance by providing an efficient way to access and manipulate data.

Key Constraints

• NOT NULL: Ensures that a key attribute cannot be null.
• UNIQUE: Ensures that a key attribute has a unique value.
• PRIMARY KEY: Ensures that a key attribute is a primary key.
• FOREIGN KEY: Ensures that a key attribute is a foreign key that references a primary key in another relation.

इस क्विज़ में डेटाबेस प्रबंधन प्रणाली (DBMS) में इस्तेमाल होने वाले कुंजी प्रकारों के बारे में जानें। सुपर की, कैंडिडेट की, प्रIMARY की, अल्टरनेट की, कंपोजिट की और फॉरेन की जैसे प्रकार शामिल हैं।