Advanced SQL Interview Questions For Data Analyst ( Most Asked )

SQL is the most important skill for any Data Analyst or Data Scientist and it is usually the first skill you will be tested during and interview related to Data Domain.

So if you are a data analyst preparing for your next interview? Then in this article is just for you

In this article we will discuss some Advanced SQL Interview Questions For Data Analyst that you must master to clear your next Data Interview.

Advanced SQL Interview Questions For Data Analyst

So here are the top Advanced SQL Interview Questions For Data Analyst that will help you for your next interview.

Just do not go through these question , try to understand the logic behind them so that you can solve them even if they are little bit twisted which is usually the case.

1 – Finding the nth Highest amount

Question: Write a query to find the 3rd highest salary in the employees table.

Solution: Use the DISTINCT keyword with a subquery and the LIMIT clause.

Distinct – To get unique values.

Limit – To limit of results you get.

Offset – To skip number of results.

Here, we order the salaries in descending order and skip the first two, returning the third highest.

2 – Find Salaries Above the Department’s Average Salaries

Question: Find the employees who have salaries above the average salary as per their their departments.

Solution: Use a correlated subquery.

In above query first we get employee id , name and salary and then we use Where keyword and “>” to get values which are greater than the average salary values we wrote in the sub query that gives us average salary as per department.

Where – To filter query as per a condition.

Avg – To find average.

3 – Get results based on Window Functions.

Question: Order employees based on their salary using the RANK() function.

Solution: Use SQL window functions.

Above query will assign a rank to each employee based on their salary in descending order

RANK() – It assigns the same rank with gaps for equal values

4. Find Consecutive Days .

Question: Find employees who attended work for three consecutive days.

Solution: Use the LEAD() and LAG() window functions

In above query lag() gives value 1 day previous to current and lead() gives value 1 day next and if there is no between all these then the employee is present for three days.

Lead() – Gives one next value.

Lag() – Gives one previous value.

Datediff() – Gives the difference between dates.

5- Identify Duplicate Records in a Table

Question: Write a query to identify duplicate orders in a table

Solution: Aggregate the output with group by and having query.

Above query groups the data as per order id and then filters it out where the order count is greater than 1 thus considered as duplicate.

Group By – Groups the results with certain column or condtion.

Having – Filters the results as per certain condition.

Related – Important SQL Topic Every Data Analyst Needs To Master

Conclusion

SQL is very important skills if you want to work in data domain .

Above provided question will help to understand most asked and most used topics in SQL. If you want to step ahead from crowd than you have to master these Advanced SQL Interview Questions For Data Analyst.

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