Senario Based SQL question

Beginner Level

1. Basic SELECT Statement

   • Scenario: You have a table named employees with columns id, name, and salary. Write a query to retrieve all employee names and their salaries.
   • Question: How would you write this query?

2. Filtering Data

   • Scenario: You want to find employees who earn more than $50,000 from the employees table.
   • Question: What SQL query would you use?

3. Sorting Data

   • Scenario: You want to list all employees in the employees table sorted by their names in alphabetical order.
   • Question: Write the SQL query to achieve this.

4. Counting Rows

   • Scenario: You need to count how many employees work in each department in the employees table.
   • Question: How would you write the query for this?

5. Using WHERE Clause

   • Scenario: You want to retrieve all employees from the employees table who are in the "Sales" department.
   • Question: What is the SQL query for this?

6. Using LIKE Operator

   • Scenario: You want to find all employees whose names start with "J" from the employees table.
   • Question: Write the SQL query.

7. Aggregate Functions

   • Scenario: You want to find the average salary of all employees in the employees table.
   • Question: How would you write this SQL query?

8. Using DISTINCT

   • Scenario: You want to find unique job titles from the employees table.
   • Question: What SQL query would you use?

9. Date Functions

   • Scenario: You need to find employees hired after January 1, 2020.
   • Question: Write the SQL query to accomplish this.

10. Basic JOIN Operation

    • Scenario: You have a departments table and an employees table. Write a query to find employee names along with their department names.
    • Question: What SQL statement would you use?

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Intermediate Level

11. Grouping Data

    • Scenario: You need to count how many employees are in each department and display it along with the department name.
    • Question: Write the SQL query.

12. HAVING Clause

    • Scenario: You want to list departments with more than 5 employees.
    • Question: What SQL query would you write?

13. Self Join

    • Scenario: You have an employees table. Write a query to find pairs of employees who work in the same department.
    • Question: How would you approach this?

14. Subquery in SELECT

    • Scenario: You want to retrieve employee names and their salary, along with the average salary of their department.
    • Question: Write the SQL query.

15. Using UNION

    • Scenario: You have two tables, contract_employees and permanent_employees. Write a query to list all employee names from both tables.
    • Question: How would you write this?

16. Window Functions

    • Scenario: You need to calculate a running total of salaries in the employees table.
    • Question: Write the SQL query using window functions.

17. CTEs (Common Table Expressions)

    • Scenario: You want to list the top 5 highest-paid employees in the company.
    • Question: How would you write this query using a CTE?

18. JSON Data Handling

    • Scenario: You have a products table with a JSON column for attributes. How would you retrieve specific attributes from this JSON column?
    • Question: Write the SQL query.

19. Multiple Joins

    • Scenario: You need to join employees, departments, and locations tables to find the names of employees and their respective department locations.
    • Question: How would you approach this?

20. Data Modification

    • Scenario: You need to increase the salary of employees in the "IT" department by 10%.
    • Question: What SQL statement would you use?

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Advanced Level

21. Complex Subqueries

    • Scenario: You want to find employees who earn more than the average salary of their respective departments.
    • Question: Write the SQL query.

22. Pivot Tables

    • Scenario: You have a sales table with sales data for different products over months. Write a query to display total sales per product per month.
    • Question: How would you achieve this?

23. Indexing

    • Scenario: You need to improve the performance of a query retrieving employee records based on their department. What type of index would you create?
    • Question: Explain your reasoning.

24. Stored Procedures

    • Scenario: You want to create a stored procedure to add a new employee to the database.
    • Question: How would you write this procedure?

25. Triggers

    • Scenario: You want to create a trigger that automatically updates the employee's last modified date whenever a record is updated.
    • Question: What would the SQL for this trigger look like?

26. Data Validation

    • Scenario: You want to ensure that no employee has a salary below the minimum wage before inserting a new record.
    • Question: How would you implement this validation?

27. Normalization

    • Scenario: You have a denormalized table with repetitive data. How would you design it to follow normalization rules?
    • Question: Describe the process.

28. Handling NULL Values

    • Scenario: You want to replace NULL values in the salary column with 0 in the employees table.
    • Question: Write the SQL query.

29. Transaction Management

    • Scenario: You need to ensure that salary updates for multiple employees occur as a single transaction.
    • Question: How would you implement this using SQL?

30. Performance Tuning

    • Scenario: You have a query that runs slowly. What steps would you take to analyze and optimize its performance?
    • Question: Explain your approach.

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Expert Level

31. Data Warehousing

    • Scenario: You need to design a data warehouse schema for a retail company, including fact and dimension tables.
    • Question: Describe your schema design.

32. Data Migration

    • Scenario: You need to migrate data from an old system to a new SQL database. What steps would you take to ensure data integrity?
    • Question: Explain the process.

33. Handling Concurrency

    • Scenario: Multiple users are updating the same employee record simultaneously. How would you manage this situation?
    • Question: Discuss your approach.

34. Advanced Window Functions

    • Scenario: You want to calculate the difference in sales between the current and previous month for each product.
    • Question: Write the SQL query using window functions.

35. Recursive CTEs

    • Scenario: You have an organizational chart stored in a table. Write a query to find all employees under a specific manager.
    • Question: How would you write this using a recursive CTE?

36. Materialized Views

    • Scenario: You need to create a materialized view for frequently accessed data to improve performance. What are the considerations?
    • Question: Explain your approach.

37. Partitioning

    • Scenario: You have a large table that stores transaction data. How would you partition this table to improve performance?
    • Question: Discuss your strategy.

38. ETL Processes

    • Scenario: You need to design an ETL process to extract data from multiple sources, transform it, and load it into a SQL database.
    • Question: Describe the steps involved.

39. Using SQL with Big Data

    • Scenario: You want to analyze large datasets stored in Hadoop using SQL. What tools or frameworks would you use?
    • Question: Explain your choice.

40. Database Security

    • Scenario: You are tasked with securing sensitive data in a SQL database. What measures would you implement?
    • Question: Discuss your security strategy.

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Specialized Level

41. Graph Queries

    • Scenario: You need to write a query to find relationships between customers based on their purchases.
    • Question: How would you approach this using graph databases?

42. Time Series Data Analysis

    • Scenario: You want to analyze sales trends over time using a time series database.
    • Question: What SQL functions would you use?

43. Multi-Tenant Database Design

    • Scenario: You need to design a database schema to support multiple clients securely.
    • Question: Describe your approach.

44. Handling Temporal Data

    • Scenario: You need to track changes in employee data over time, including historical records.
    • Question: How would you implement this?

45. Data Quality Management

    • Scenario: You want to ensure data accuracy and consistency in your SQL database.
    • Question: What strategies would you employ?

46. SQL and NoSQL Integration

    • Scenario: You have both SQL and NoSQL databases in

your application. How would you manage data across both?

• Question: Discuss your integration strategy.

47. Event-Driven SQL Queries

    • Scenario: You need to create a system that triggers SQL queries based on specific events (like new data entries).
    • Question: How would you implement this?

48. Change Data Capture (CDC)

    • Scenario: You want to track changes in a table for auditing purposes. What approach would you take?
    • Question: Describe the implementation.

49. API Integration with SQL

    • Scenario: You need to integrate an external API to fetch data and store it in your SQL database.
    • Question: Explain how you would handle this.

50. Advanced Query Optimization Techniques

    • Scenario: You have a complex query that takes too long to execute. What advanced techniques would you use to optimize it?
    • Question: Discuss your approach.