W Energy Software SQL Developer Interview Questions, Process, and Tips

30 mins duration. Reasoning

Q1. What is SQL and Database?
Ans. 
SQL is a programming language used for managing and manipulating relational databases.
• SQL stands for Structured Query Language.

• It is used to communicate with and manage databases.

• SQL allows users to create, modify, and retrieve data from databases.

• It is a standard language for relational database management systems (RDBMS).

• SQL is used for tasks like data insertion, deletion, updating, and querying.

• Examples of popular R...read more
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Q2. What are Constraints?
Ans. 
Constraints are rules applied to a database table to enforce data integrity and ensure accuracy.
• Constraints define limits or conditions on the data that can be inserted, updated, or deleted in a table.

• They help maintain data consistency and prevent invalid or inconsistent data from being stored.

• Common types of constraints include primary key, foreign key, unique, not null, and check constraints.

• Examples: A primary key ...read more
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Q1. What is the Primary Key?
Ans. 
Primary Key is a unique identifier for each record in a database table.
• Primary Key ensures data integrity by enforcing uniqueness and preventing duplicate records.

• It is used to establish relationships between tables in a database.

• Primary Key can be a single column or a combination of multiple columns.

• It is often used as a reference in foreign key constraints.

• Examples of Primary Keys include social security numbers, ema
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Q1. Tell us about your previous experience?
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Q1. What is SQL Injection?
Ans. 
SQL Injection is a code injection technique where an attacker inserts malicious SQL statements into a query to manipulate the database.
• SQL Injection is a common web application vulnerability.

• It occurs when user-supplied input is not properly validated or sanitized.

• Attackers can exploit SQL Injection to bypass authentication, retrieve sensitive data, modify or delete data, or even execute arbitrary commands.

• Preventing S...read more
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30 mins duration - Reasoning

Q1. Explain SQL Constraints? What is data integrity?
Ans. 
SQL constraints are rules that are applied to a table's columns to ensure data integrity.
• Constraints are used to enforce rules and restrictions on data in SQL tables.

• They help maintain data integrity by preventing invalid or inconsistent data from being inserted or updated.

• Common types of constraints include primary key, foreign key, unique, and check constraints.

• For example, a primary key constraint ensures that each ...read more
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Q1. Why this role attract you?
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Q1. What brought you here?
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Q1. Can you work under pressure?
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30 mins duration - verbal ability

Q1. What is the usage of the NVL() function? What is cursor? How to use a cursor?
Ans. 
The NVL() function is used to replace NULL values with a specified value.
• NVL() is commonly used in SQL queries to handle NULL values.

• It takes two arguments: the value to be checked and the replacement value.

• If the value is NULL, the function returns the replacement value.

• If the value is not NULL, the function returns the original value.

• Example: SELECT NVL(column_name, 'N/A') FROM table_name;
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