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"How to Extract the Top 3 Highest Salaries in SQL Without Using LIMIT or RANK"

 
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Jan 12, 2025 3:00 pm
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Introduction
When dealing with databases, extracting specific data insights efficiently is crucial. A common task is fetching the top values like salaries, sales figures, or scores. However, what if you need to extract the top 3 highest salaries in SQL without relying on functions like LIMIT or RANK? This post will walk you through this unique challenge with SQL queries and explanations. Whether you're preparing for interviews or enhancing your SQL skills, this solution is a must-know.

Understanding the Challenge
Functions like LIMIT or RANK are often used to solve these problems. However, not all database systems support these functions natively. Therefore, mastering alternative solutions is vital for working with legacy systems or specific database setups.

Example Table: Employee
Here’s a sample Employee table we'll use:

EmployeeID Name Salary
1 Alice 95000
2 Bob 87000
3 Charlie 105000
4 Diana 92000
5 Edward 98000

Query to Extract Top 3 Salaries

Instead of using advanced SQL functions, we can leverage subqueries and conditional logic. Here's how:

sql
 
SELECT DISTINCT Salary
FROM Employee E1
WHERE 3 > (
SELECT COUNT(DISTINCT Salary)
FROM Employee E2
WHERE E2.Salary > E1.Salary
)
ORDER BY Salary DESC;

Explanation of the Query

  1. Outer Query:

    • SELECT DISTINCT Salary ensures that duplicate salaries are not repeated in the result.
    • The outer query iterates over each salary in the Employee table.

  2. Inner Query:

    • (SELECT COUNT(DISTINCT Salary) FROM Employee E2 WHERE E2.Salary > E1.Salary) calculates how many salaries are greater than the current salary being evaluated by the outer query.

  3. Condition:

    • 3 > filters the rows where fewer than 3 salaries are greater than the current one. This ensures only the top 3 salaries are selected.

  4. ORDER BY:

    • The ORDER BY Salary DESC arranges the top 3 salaries in descending order.

Testing the Query
Running the query against our sample Employee table will return:

Salary
105000
98000
95000

Real-World Applications

  • Performance Reviews: Identify the top 3 earners in your company.
  • Sales Analysis: Fetch top-performing regions or products.
  • Exam Scores: List the top 3 student scores in a competitive exam.

Benefits of This Approach

  • Compatible with older databases that don’t support advanced functions.
  • Provides a deeper understanding of SQL logic.

Common Mistakes to Avoid

  1. Forgetting to use DISTINCT can lead to incorrect results with duplicate salaries.
  2. Omitting the ORDER BY clause may produce unordered results.
  3. Applying the query on large datasets without proper indexing may impact performance.

Conclusion
This method of extracting the top 3 highest salaries without using LIMIT or RANK is a powerful addition to your SQL toolkit. Whether you're using SQL for work or study, understanding such alternative techniques will set you apart.

If you found this tutorial helpful, share it with others! For more SQL insights and challenges, explore www.sqlqueries.in/community.

Topic Tags
extract top 3 highest sal SQL query without LIMIT SQL alternative to RANK SQL top salaries query advanced SQL interview q

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Topic Tags:  extract top 3 highest sal (1) , SQL query without LIMIT (1) , SQL alternative to RANK (1) , SQL top salaries query (1) , advanced SQL interview q (1) ,
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