Senior Programmer Interview Questions and Answers

Duplicate data can be deleted by using SQL queries with the DISTINCT keyword or by writing a script to identify and remove duplicates.

• Use SQL queries with the DISTINCT keyword to select unique records and insert them into a new table.

• Write a script to iterate through the data, identify duplicates based on specific criteria, and delete them.

• Utilize built-in functions or libraries in programming languages like Python or Java to remove duplicate entries.

SQL questions often assess knowledge of database management, querying, and optimization techniques.

• Understand SQL basics: SELECT, INSERT, UPDATE, DELETE.

• Know how to use JOINs: INNER JOIN, LEFT JOIN, RIGHT JOIN.

• Familiarity with aggregate functions: COUNT(), SUM(), AVG().

• Be able to write subqueries and understand their use cases.

• Understand indexing and its impact on query performance.

Encapsulation is the concept of bundling data and methods that operate on the data into a single unit.

• Encapsulation helps in hiding the internal state of an object and only exposing necessary functionalities.

• It allows for better control over the data by preventing direct access from outside the class.

• Encapsulation promotes code reusability and modularity by keeping related data and methods together.

• Example: In a class representing a car, encapsulation would involve private va...read more

Transactions in SQL server ensure data integrity by grouping multiple SQL statements into a single unit of work.

• Transactions help maintain data consistency by either committing all changes or rolling them back if an error occurs.

• Use BEGIN TRANSACTION to start a transaction, COMMIT to save changes, and ROLLBACK to undo changes.

• Example: BEGIN TRANSACTION; UPDATE table SET column = value; COMMIT; - commits the changes made in the transaction.

Create an SMS system in JavaScript

• Use Twilio API for sending SMS messages

• Implement a backend server to handle incoming and outgoing messages

• Store message data in a database for tracking and logging

A view in SQL server is a virtual table that contains the result set of a SELECT statement.

• Views are used to simplify complex queries by storing them as a virtual table.

• Views can be used to restrict access to specific columns or rows of a table.

• Views can improve performance by pre-computing expensive queries.

• Example: CREATE VIEW vwEmployee AS SELECT FirstName, LastName FROM Employees;

Function to reverse an array of strings

• Create a function that takes an array of strings as input

• Use a loop to iterate through the array and reverse each string

• Return the reversed array of strings