10+ JNET Technologies Interview Questions and Answers

Types of state management in React include local state, props, context API, Redux, and MobX.

• Local state: State managed within a component using useState hook.

• Props: Data passed from parent to child components.

• Context API: Allows sharing state across multiple components without prop drilling.

• Redux: External state management library for managing complex state in large applications.

• MobX: Another external state management library that uses observables to manage state.

HTML and CSS are languages used for creating and styling web pages.

• HTML stands for HyperText Markup Language and is used for creating the structure of a web page.

• CSS stands for Cascading Style Sheets and is used for styling the elements on a web page.

• HTML uses tags to define different elements like headings, paragraphs, images, and links.

• CSS allows for customization of colors, fonts, layouts, and other visual aspects of a web page.

• Both HTML and CSS are essential for web devel...read more

Prop drilling is the process of passing down props from a parent component to nested child components, even if the intermediate components do not use the props.

• Prop drilling can lead to unnecessary passing of props through multiple levels of components.

• It can make the code harder to maintain and understand.

• One way to avoid prop drilling is by using context API or state management libraries like Redux.

• Example: Parent component passes a prop to Child component, which then passe...read more

Reconciliation is the process of comparing two sets of records to ensure they are in agreement.

• Reconciliation involves verifying and adjusting financial transactions to ensure accuracy.

• It is commonly used in accounting to match transactions in bank statements with internal records.

• Reconciliation helps identify discrepancies and errors that need to be resolved.

• Examples include reconciling credit card statements with receipts and reconciling inventory records with physical coun...read more

React JS is a JavaScript library for building user interfaces.

• React JS is developed and maintained by Facebook.

• It allows developers to create reusable UI components.

• React uses a virtual DOM for better performance.

• It follows a component-based architecture.

• React can be used for building single-page applications.

Redux is a predictable state container for JavaScript apps. Context API is a way to pass data through the component tree without having to pass props down manually.

• Redux is a state management library commonly used with React to manage application state in a predictable way.

• Redux follows a unidirectional data flow pattern, where the state of the whole application is stored in a single store.

• Actions are dispatched to update the state in Redux, and reducers specify how the state...read more

Refresh mechanism in SQL is used to update the data in a materialized view or a snapshot to reflect changes in the base tables.

• Refresh mechanism can be manual or automatic.

• Manual refresh requires the user to explicitly refresh the materialized view using a command like REFRESH MATERIALIZED VIEW.

• Automatic refresh can be set up using options like ON COMMIT or ON DEMAND.

• Examples of automatic refresh include fast refresh and complete refresh.

• Fast refresh updates only the changed ...read more

Performance tuning involves optimizing the speed and efficiency of a system or application.

• Identifying and resolving bottlenecks in the system

• Optimizing SQL queries by adding indexes, rewriting queries, or using hints

• Tuning database parameters such as memory allocation and buffer sizes

• Using tools like Explain Plan to analyze query performance

• Caching frequently accessed data to reduce load on the database

SQL Loader is a tool provided by Oracle for loading data from external files into database tables.

• SQL Loader is used to load data from flat files (such as CSV) into Oracle database tables.

• It can handle large volumes of data efficiently.

• Control files are used to specify the format of the data file and the target table columns.

• SQL Loader can perform various data transformations during the loading process.

• It is commonly used for bulk data loading tasks.

• Example: sqlldr username/p...read more

Lead and Lag are analytic functions in SQL used to access data from a previous or subsequent row in a result set.

• Lead function is used to access data from a subsequent row in the result set.

• Lag function is used to access data from a previous row in the result set.

• Both functions take three arguments: the column to retrieve data from, the number of rows forward or backward to look, and a default value if the offset goes beyond the bounds of the result set.

• Example: SELECT employ...read more