Introudction to dbms and RDMBS_Presentation.pptx

RDBNS ppts for new users

1. Relational Data Model (RDMBS) Key Concepts Your Name/Institution

2. Introduction to RDMBS The Relational Data Model (RDMBS) is a way to structure and query data using tables, which are also called relations. It is the most widely used data model for databases.

3. Attributes An attribute is a characteristic or parameter for which data are stored in a relation. Simply stated, the columns of a relation are the attributes, which are also referred to as fields.

4. Tuples Each row of data in a relation (table) is called a tuple. A tuple represents a single data item in the table.

5. Domains A domain is a set of values from which an attribute can take a value in each row. Usually, a data type is used to specify the domain for an attribute. For example, in the STUDENT relation, the attribute RollNumber takes integer values, hence its domain is a set of integer values.

6. Degree The number of attributes in a relation is called the Degree of the relation. For example, a table with 5 columns has a degree of 5.

7. Cardinality Cardinality refers to the number of tuples (rows) in a relation (table). For example, a table with 50 rows has a cardinality of 50.

8. Database Keys Keys are crucial in relational databases as they ensure each record within a table is uniquely identifiable. There are several types of keys, each serving a different purpose.

9. Primary Key A primary key is a unique identifier for a tuple in a relation. Each table can have only one primary key, which ensures that no two rows have the same value for this key.

10. Foreign Key A foreign key is an attribute that creates a link between two tables. It is a field in one table that is the primary key in another table, establishing a relationship between the two tables.

11. Candidate Key A candidate key is an attribute, or a set of attributes, that can uniquely identify a tuple in a relation. Each table can have multiple candidate keys, but only one primary key.

12. Alternate Key An alternate key is any candidate key that is not chosen as the primary key. These keys are still unique identifiers for tuples but serve as alternatives to the primary key.

13. Conclusion Understanding the key concepts of the Relational Data Model is essential for working with databases. Attributes, tuples, domains, degrees, and cardinality, along with various types of keys, form the foundation of database management.

14. Q&A Questions and Answers