Basics - A Historical Perspective
- File Systems v/s DBMS
- Data Models
- Levels of Abstraction
- Structure of DBMS
- Database Design
- Database Design
- ER Diagrams
- Attributes
- Entity
- Relationships
- Additional Features of the ER Model
- Relational Model
- Introduction to the Relational Model
- Integrity constraint over relations
- Enforcing Integrity Constraints
- Querying Relational Data
- Views
- Relational Algebra
- Tuple Relational Calculus
- SQL
- Form of basic SQL query
- UNION
- INTERSECT
- EXCEPT
- Aggregation Operators
- Complex Integrity Constraints in SQL
- Triggers and Active data bases
- Schema Refinement
- Problems caused by redundancy
- Decompositions and its problems
- Functional Dependencies and its reasoning
- Introduction to Normal Forms
- First Normal Form (1NF)
- Second Normal Form (2NF)
- Third Normal Form (3NF)
- Boyce-Codd Normal Form (BCNF)
- Fourth Normal Form (4NF)
- Fifth Normal Form (5NF or PJNF)
- Sixth Normal Form (6NF)
- Transaction
- Transaction Concept
- Transaction State
- Implementation of Atomicity and Durability
- Concurrent Executions
- Serializability
- Recoverability
- Implementation of Isolation
- Lock Based Protocols
- Timestamp Based Protocols
- Validation Based Protocols
- Multiple Granularity
- Recovery and Atomicity in dbms
- Recovery with Concurrent Transactions
- Indexing
- Data on External Storage
- File Organization and Indexing
- Cluster Indexes
- Primary Indexes
- Secondary Indexes
- Index data Structures
- Comparison of File Organizations, Indexes and Performance Tuning
- Indexed Sequential Access Methods
- Dynamic Index Structure - B+ Tree
Introduction to the Relational Model in DBMS
The Relational Model(RM) for database management is an approach to logically represent and manage the data stored in a database. In this model, the data is organized into a collection of two-dimensional inter-related tables, also known as relations. Each relation is a collection of columns and rows, where the column represents the attributes of an entity and the rows (or tuples) represents the records.
Terminologies used in Realation Model
- Tables: relations are saved in the table format. A table has two properties rows and columns
- Attribute: columns represent as attributes
- Tuple: A Row represent as Tuple
- Relation Schema: A relation schema represents the name of the relation with its attributes.
- Degree: The total number of attributes which in the relation is called the degree of the relation.
- Cardinality: Total number of rows present in the Table.
- Column: The column represents the set of values for a specific attribute.
- Relation instance: The set of tuples of a relation at a particular instance of time is called as relation instance.
Advantages of Realation Model
- Structural Independence: Structural independence is an ability that allows us to make changes in one database structure without affecting other. The relational model have structural independence. Hence making required changes in the database is convenient in relational database model.
- Conceptual Simplicity: The relational model allows the designer to simply focus on logical design and not on physical design. Hence relational models are conceptually simple to understand.
- Query Capability: Using simple query language (such as SQL) user can get information from the database or designer can manipulate the database structure.
- Easy design,maintenance and usage: The relational models can be designed logically hence they are easy to maintain and use.
Disadvantages of Realation Model
- Relational model requires powerful hardware and large data storage devices.
- May lead to slower processing time.
- Poorly designed systems lead to poor implementation of database systems.
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