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Articles on Trending Technologies
Technical articles with clear explanations and examples
Commercial Database
A Commercial Database is a paid database service designed for users who need access to large volumes of specialized information. These databases are subject-specific, containing vast amounts of curated data that individual organizations cannot afford to collect and maintain on their own. Access is provided through commercial links or subscription plans. Characteristics Paid access − Users pay a subscription fee or per-query charge to access the data. Subject-specific − Each database focuses on a particular domain (medical, legal, financial, scientific, etc.). Large scale − Contains huge volumes of curated, verified information. Professionally maintained − Data is regularly ...
Read MoreEnd User Database
An End User Database is a shared database specifically designed for end users who are not concerned with the underlying transactions, operations, or technical details. The end user interacts only with the final product − a software application or interface − and the database presents summarized, meaningful information for their use. Characteristics User-friendly − Designed for non-technical users who interact through simple interfaces. Summarized data − Contains aggregated and processed information rather than raw transactional data. Shared access − Multiple end users (managers, staff, customers) can access the same database. Abstraction − Hides the complexity of underlying ...
Read MorePersonal database
A Personal Database is a small, single-user database that is stored and managed on a personal computer. The data is collected and used by an individual or a small group of people, typically within the same department of an organization. Characteristics Single-user − Designed for one user or a small group at a time. Small size − Stores limited amounts of data, easily manageable on a personal computer. Simple structure − Does not require complex database administration. Local storage − Data resides on the user's personal computer or local drive. Department-level − Generally used within a single ...
Read MoreEntity Relationship Participation in Database
In a relationship, the Participation Constraint specifies the existence of an entity when it is related to another entity. It is also called the minimum cardinality constraint and specifies the number of instances of an entity that can participate in a relationship type. There are two types − Total Participation and Partial Participation. Total Participation In total participation, each entity in the entity set must be involved in at least one relationship instance. No entity can exist without participating in the relationship. Example − Consider two entities Employee and Department related via the Works_For relationship. Every employee ...
Read MoreTernary Relationship in Database
In a Ternary Relationship, three different entities participate in a single relationship simultaneously. The relationship degree is 3. When determining cardinality, we consider it in the context of two entities relative to the third. Example: Mobile Manufacturing Company Consider a mobile manufacturing company with three entities − Mobile − The mobile models manufactured by the company. Part − Mobile parts which the company gets from suppliers. Supplier − Suppliers who supply mobile parts to the company. All three entities participate simultaneously in a SUPPLIES relationship ? ...
Read MoreBinary Relationship in Database
A Binary Relationship is a relationship between two different entities. It maps the role group of one entity with the role group of another entity. There are three types of cardinalities for binary relationships − One-to-One, One-to-Many, and Many-to-Many. One-to-One (1:1) One instance of one entity is mapped with only one instance of another entity. The primary key of one entity is available as a foreign key in the other entity. Example − Consider two entities Person and Driver_License. One person should have only one driving license number. The relationship from Driver_License to Person is compulsory (every ...
Read MoreOne-to-One Unary Relationship in DBMS
A One-to-One Unary Relationship (also called a recursive relationship) is an association within the same entity where one instance is related to exactly one other instance of the same entity type. Example: MARRIED_TO Relationship Consider a set of married persons. The entity "Person" has a relationship MARRIED_TO with itself − each person is married to one and only one other person in the same group ? Person MARRIED_TO ...
Read MoreSixth Normal Form (6NF)
In Sixth Normal Form (6NF), a relation variable is decomposed into its irreducible components − each table contains at most the primary key and one non-key attribute. A relation is in 6NF only if it is already in 5NF and every join dependency on the relation is trivial. Example 1: Student Table Consider the following Student table ? Enrollment_No Name Marks The possible join dependencies are − {Enrollment_No, Name} {Enrollment_No, Marks} In 6NF, this is decomposed into two irreducible tables − StudentInformation Enrollment_No ...
Read MoreUnique Key in RDBMS
A Unique Key is a constraint in RDBMS that ensures all values in a column (or set of columns) are distinct. Many users confuse Primary Key with Unique Key since both enforce uniqueness, but they differ in NULL handling, volume, and modifiability. Primary Key vs Unique Key Feature Primary Key Unique Key Purpose Provides uniqueness and identifies each row Prevents duplicate values in a column NULL Values Cannot accept NULL Allows one NULL value Count Per Table Only one per table Multiple allowed per table Modification Cannot be ...
Read MoreRDBMS terminologies
RDBMS (Relational Database Management System) uses specific terminologies to describe its components. These include Database, Table, Column, Row, and various types of keys. Let us see them one by one − Database A database is a collection of related tables. For example, a university database may contain tables like Student, Professors, Courses, etc. Table A table (also called a relation) is a collection of rows and columns that stores data about a specific entity ? StudentId StudentName StudentRank 052 Tom 1 035 David 2 077 John 3 ...
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