Tuesday, 12 January 2016

4 Ways to find Nth highest salary in SQL - Oracle, MSSQL and MySQL

One of the most common SQL interview questions is to find the Nth highest salary of employee, where N could be 2, 3, 4 or anything e.g. find the second highest salary in SQL. Sometimes this question is also twisted as to find the nth minimum salary in SQL. Since many Programmers only know the easy way to solve this problem e.g. by using SQL IN clause, which doesn't scale well, they struggle to write the SQL query when Interviewer keep asking about 4th highest, 5th highest and so on. In order to solve this problem effectively, you need to know about some key concepts like correlated subquery, window functions like ROW_NUMER(), RANK() and DENSE_RANK() etc. Once you know the generic logic to solve this problem, you can tackle all those variations by yourself.
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