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Eltus Mode Interview Questions and Answers
Q1. how many columns can be created in table?
The number of columns that can be created in a table depends on the database management system being used.
The limit varies depending on the DBMS
For MySQL, the limit is 4096 columns per table
For Oracle, the limit is 1000 columns per table
The number of columns can also be limited by the available memory and disk space
Q2. Types of Design Patterns and explain any one
Design patterns are reusable solutions to common software problems. One example is the Singleton pattern.
Creational patterns: Singleton, Factory, Abstract Factory, Builder
Structural patterns: Adapter, Bridge, Composite, Decorator, Facade, Flyweight, Proxy
Behavioral patterns: Chain of Responsibility, Command, Interpreter, Iterator, Mediator, Memento, Observer, State, Strategy, Template Method, Visitor
Singleton pattern ensures a class has only one instance, and provides a globa...read more
Q3. Explain in details about Oops concepts
OOPs concepts are the fundamental principles of object-oriented programming.
Encapsulation - binding data and functions together
Inheritance - creating new classes from existing ones
Polymorphism - ability of objects to take on multiple forms
Abstraction - hiding implementation details from users
Q4. Which is master database
Master database is the primary database that stores all the important data of an organization.
Master database is the central repository of all the important data of an organization
It is used to store and manage critical data such as customer information, financial data, and employee records
It is usually the most secure and highly available database in an organization
Examples of master databases include Oracle, SQL Server, and MySQL
Q5. what are the data types in JS
Data types in JavaScript include number, string, boolean, object, function, undefined, and null.
Number - represents numeric data, e.g. 10, 3.14
String - represents textual data, e.g. 'hello', '123'
Boolean - represents true or false values, e.g. true, false
Object - represents complex data structures, e.g. { key: 'value' }
Function - represents executable code, e.g. function() { }
Undefined - represents a variable that has not been assigned a value
Null - represents an intentional ...read more
Q6. what are closures
Closures are functions that have access to variables from their containing scope even after the scope has closed.
Closures allow functions to access variables from their outer function even after the outer function has finished executing.
They are commonly used in event handlers, callbacks, and asynchronous programming.
Closures help in maintaining state in functional programming.
Q7. what is virtual DOM
Virtual DOM is a lightweight copy of the actual DOM used for efficient updates in web development.
Virtual DOM is a concept used in frameworks like React to improve performance by minimizing actual DOM manipulations.
When changes are made to the virtual DOM, a comparison is done with the actual DOM to determine the minimal updates needed.
This approach reduces the number of costly DOM operations, resulting in faster rendering and improved user experience.
Q8. write react code for counter
React code for a simple counter
Create a functional component for the counter
Use useState hook to manage the count state
Render the count value and buttons to increment and decrement the count
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