Lossless Decomposition
Lossless Decomposition Lossless decomposition refers to the process of decomposing a relation (or table) into two or more smaller relations (tables) in such a way that no information is lost when the tables are joined back together. The lossless property ensures that the original data can be fully reconstructed by joining the decomposed relations, preserving […]
Decomposition in DBMS
Decomposition in DBMS Decomposition in Database Management Systems (DBMS) refers to the process of breaking down a relation (or table) into smaller, simpler relations while ensuring that no information is lost. Decomposition is an important technique in database normalization, where we break down large, complex tables into smaller ones that meet the criteria of normal […]
Important Points of Normal Forms
Important Points Of Normal Forms As we know, normalization is used to remove the redundancy in the database. Types of normal forms are given below. Important points about normal form are given below Point-01: A relation in 5NF will always be in all other normal forms as 4NF, BCNF, 3NF, 2NF, and 1NF. In the […]
5NF in DBMS
5NF in DBMS Fifth Normal Form (5NF), also known as Project-Join Normal Form (PJNF), is the highest level of database normalization. A table is said to be in 5NF if: It is in Fourth Normal Form (4NF). It has no join dependency and it is not reducible further. In 5NF, a relation (table) is decomposed […]
4NF in DBMS
4NF in DBMS Fourth Normal Form (4NF) is a higher level of database normalization that aims to eliminate multivalued dependencies. A table is said to be in 4NF if: It is in Boyce-Codd Normal Form (BCNF). It has no multivalued dependencies. Notation of Multi-Valued Dependency What is a Multivalued Dependency? A multivalued dependency occurs when […]
BCNF in DBMS
BCNF in DBMS Boyce-Codd Normal Form (BCNF) is an advanced version of Third Normal Form (3NF) that eliminates any remaining anomalies that can still occur in a table that is in 3NF. A table is in BCNF if it satisfies the following conditions: It is in 3NF. For every functional dependency, the left-hand side (LHS) […]
3NF in DBMS
3NF in DBMS Third Normal Form (3NF) is a further step in database normalization that ensures data is stored efficiently by eliminating transitive dependencies. A table is in 3NF if it satisfies the following conditions: It is in 2NF: The table must first meet all the requirements of Second Normal Form (2NF). No Transitive Dependency: […]
2NF in DBMS
2NF in DBMS Second Normal Form (2NF) is a step further in database normalization that builds on the foundation established by First Normal Form (1NF). A table is in 2NF if it satisfies the following conditions: It is in 1NF: The table must first meet all the requirements of First Normal Form (1NF). No Partial […]
1NF in DBMS
1NF in DBMS In Database Management Systems (DBMS), First Normal Form (1NF) is the basic level of normalization. A relation (or table) is said to be in 1NF if it meets the following conditions: Atomicity: Each column contains only atomic (indivisible) values. This means no column should contain multiple values or sets of values (e.g., […]
Candidate vs. Super Key AND Prime vs. Non-Prime Attributes
Candidate Vs. Super Key AND Prime vs. Non-Prime Attributes Before Candidate Key Vs. For superkey and prime attributes vs. non-prime attributes, we must know about functional dependency and closure methods. Candidate Key VS Super Key A super-key is a set of attributes of a relation that are used to uniquely identify a tuple and determine […]
Redundancy Problems
Redundancy Problems Redundancy is the multiple copies of the same data in the database. It occurs when a database is not normalized. Redundancy problems can removed or reduced through Normalization. Types of Redundancy There are two types of redundancy levels, given below 1. Row-level redundancy When two rows are exactly the same, it is called […]
Inference Rules in DBMS
Inference Rules in DBMS In Database Management Systems (DBMS), Inference Rules are used to derive additional Functional Dependencies (FDs) from the initial set of attributes. These rules help in simplifying the structure of a database by logically inferring relationships between attributes, ultimately aiding in tasks like normalization. Each rule provides a way to derive new […]
Functional Dependency In DBMS
Functional Dependency In DBMS In database management systems (DBMS), functional dependency is a relationship between two sets of attributes (columns) in a database table. It defines how one attribute (or group of attributes) determines the value of another attribute. Simply put, if you know the value of one attribute, you can determine the value of […]
Equi Join
EQUI JOIN Equi Join is also known as an inner join. It is the most common join. It finds and returns the values which are based on equality conditions. Equi uses the comparison operator (=). Note: Column names for the primary and foreign keys may or may not be the same because we use the […]
Outer Join
Outer Join A Natural join finds and returns matching data from two tables, but an outer -join finds and returns some matching data and some dissimilar data as well from tables. Conditions for outer join are similar to those in natural join, where Common columns for joining must have the same name. Types of Outer […]
Natural Join
Natural Join Natural Join is the cross product of two tables where it finds and returns the matching tuples. Condition: Common columns (one as a primary key and the other as a foreign key) for joining must have the same name. Keep in mind: In natural join, columns with the same name of both joining […]
Normalization And Its Types
Normalization And Its Types Normalization is a process used in database design to organize data efficiently. The goal is to eliminate data redundancy (repeated data) and improve data integrity by dividing large tables into smaller, related ones. This technique ensures that the data is logically stored and can be accessed or updated with minimal errors […]
Extended Operators in Relational Algebra
Extended Operators in Relational Algebra Extended operators are those operators which can derive from other operators, i.e. (Unary or Binary operators). Types of Extended Operators There are 3 types of extended operators in Relational Algebra Intersection Operator Divide Operator Join Operator 1. Intersection Operator (∩) The intersection operator is the reverse of the Union operator. […]
Binary Operators in Relational Algebra
Binary Operators in Relational Algebra All those Operators that operate on two operands are known as Binary operators. Types of Binary Operators There are 3 types of binary operators, which are given below Union Operators Cross Product Difference operator 1. Union Operator (∪) Let A and B be two relations. Then A ∪ B is the […]
Unary Relational Operations in DBMS
Unary Operators in Relational Algebra All those Operators that operate on a single operand are known as unary operators in relational algebra. Unary operators are of three major types Projection Operator Selection Operator Rename Operator 1. Projection Operator Projection Operator (π) displays the columns of a table based on the specified attributes. It just works […]