20+ Virtual Galaxy Infotech Interview Questions and Answers

Master table should have a primary key which is used as a foreign key in the transaction table.

• Create a primary key in the master table

• Create a foreign key in the transaction table that references the primary key in the master table

• Use the foreign key to link the two tables on forms

Triggers used in forms and their levels and uses.

• Types of triggers: Pre-Form, Post-Form, Item, Validation, Navigation, Transaction

• Pre-Form triggers execute before the form is displayed

• Post-Form triggers execute after the form is closed

• Item triggers execute when a user interacts with an item on the form

• Validation triggers execute when a user enters data into an item

• Navigation triggers execute when a user navigates between items on the form

• Transaction triggers execute when a us...read more

Yes, exception handling is necessary in queries.

• Exception handling helps to handle unexpected errors and prevent application crashes.

• It also helps to provide meaningful error messages to the user.

• In SQL, exceptions can be handled using the TRY-CATCH block.

• In NoSQL databases, exceptions can be handled using error codes and messages.

Delete and Truncate are SQL commands used to remove data from a table, but they differ in their approach.

• DELETE is a DML command that removes specific rows from a table based on a condition.

• TRUNCATE is a DDL command that removes all the rows from a table and resets the identity of the table.

• DELETE is slower than TRUNCATE as it logs the data changes, whereas TRUNCATE does not.

• DELETE can be rolled back, but TRUNCATE cannot be rolled back.

• DELETE can be used with a WHERE clause, ...read more

Set operators are used to combine or compare sets in SQL.

• UNION operator combines two sets and removes duplicates

• INTERSECT operator returns only common elements in two sets

• EXCEPT operator returns elements in one set but not in the other

• ALL keyword can be used with set operators to include duplicates

• Set operators can only be used with compatible data types

Packages, Index, and Sequences are all related to data organization and management in programming.

• Packages are collections of related classes and interfaces that are used to organize code.

• Index is a data structure that allows for efficient searching and retrieval of data.

• Sequences are ordered collections of elements that can be accessed by their position in the sequence.

• Examples include the Java Collections Framework, which includes packages for organizing data structures lik...read more

Single row functions operate on a single row and return one result per row. Group functions operate on a group of rows and return one result per group.

• Single row functions include: numeric functions, character functions, date functions, conversion functions, and general functions.

• Group functions include: AVG, COUNT, MAX, MIN, SUM.

• Single row functions can be used in SELECT, WHERE, and ORDER BY clauses.

• Group functions are used with the GROUP BY clause.

• Examples of single row fun...read more

There are three types of loops: for, while, and do-while.

• For loop: executes a block of code a fixed number of times.

• While loop: executes a block of code as long as the condition is true.

• Do-while loop: executes a block of code at least once, then repeats as long as the condition is true.

A subquery is a query nested inside another query. It is used to retrieve data from multiple tables or perform complex calculations.

• A subquery is enclosed within parentheses and is usually placed within the WHERE or HAVING clause of the outer query.

• The result of the subquery is used by the outer query to filter or manipulate the data.

• Subqueries can be used to retrieve data from multiple tables, perform calculations, or compare values.

• Examples of subqueries include finding the...read more

Sample queries for PROCEDURE, FUNCTION, CURSOR

• PROCEDURE: CREATE PROCEDURE get_employee_details AS SELECT * FROM employees;

• FUNCTION: CREATE FUNCTION get_employee_count RETURN NUMBER IS count NUMBER; BEGIN SELECT COUNT(*) INTO count FROM employees; RETURN count; END;

• CURSOR: DECLARE emp_cursor CURSOR FOR SELECT * FROM employees; OPEN emp_cursor; FETCH emp_cursor INTO emp_record; CLOSE emp_cursor;

Procedures do not return values while functions return values.

• Procedures are used to perform an action while functions are used to calculate and return a value.

• Functions can be used in expressions while procedures cannot.

• Functions have a return type while procedures do not.

• Functions can have input parameters and return values while procedures can only have input parameters.

• Examples of functions include Math.max() and String.length() while examples of procedures include consol...read more

Reports can be categorized into operational, analytical, and statutory reports.

• Operational reports provide information on day-to-day activities.

• Analytical reports provide insights into data trends and patterns.

• Statutory reports are required by law and must be submitted to regulatory bodies.

• Other types of reports include ad hoc reports, exception reports, and dashboards.

Canvas in forms can be of different types like HTML5 Canvas, SVG Canvas, and PDF Canvas.

• HTML5 Canvas allows for drawing graphics using JavaScript

• SVG Canvas is scalable and can be manipulated with CSS

• PDF Canvas is used for generating PDF documents programmatically

A View is a user interface element that displays information or interacts with the user.

• A View is a fundamental building block of Android UI.

• It can be a button, text field, image, or any other interactive element.

• Views can be arranged in a hierarchy to create complex UI layouts.

• Each View has its own set of properties that can be customized, such as size, color, and behavior.

There are various types of forms used in software development.

• Web Forms - used for collecting user input on a website

• Windows Forms - used for creating desktop applications

• Mobile Forms - used for creating mobile applications

• Dialog Forms - used for displaying messages or alerts to the user

• Modal Forms - used for capturing user input before allowing further interaction

• Wizard Forms - used for guiding the user through a multi-step process

The addAll() method is used to add all elements of one ArrayList to another.

• Use the addAll() method to add all elements of one ArrayList to another

• Syntax: list1.addAll(list2);

• Example: ArrayList list1 = new ArrayList<>(); list1.addAll(Arrays.asList(1, 2, 3));

Collection Framework is a unified architecture for representing and manipulating collections of objects in Java.

• It provides interfaces (List, Set, Queue, etc.) and classes (ArrayList, HashSet, PriorityQueue, etc.) to store and manipulate groups of objects.

• Collections can be easily sorted, searched, and iterated using methods provided by the Collection Framework.

• Example: ArrayList is a class that implements the List interface and allows for dynamic resizing of the collection.

Constraints are rules enforced on data in a table, while triggers are actions performed in response to certain events.

• Constraints ensure data integrity and consistency, while triggers automate actions based on specific events.

• Constraints are defined at the time of table creation, while triggers are created separately.

• Constraints can be used to enforce rules such as unique values, primary keys, and foreign keys, while triggers can be used to perform actions such as logging cha...read more

RestApi is a set of rules and conventions for building and interacting with web services using HTTP methods.

• RestApi stands for Representational State Transfer Application Programming Interface.

• It allows communication between different software systems over the internet.

• RestApi uses standard HTTP methods like GET, POST, PUT, DELETE for data manipulation.

• JSON or XML formats are commonly used for data exchange in RestApi.

• Example: Twitter API allows developers to access and inter...read more