Writing an SQL Query That Works in Both MySQL and PostgreSQL

Writing a Query that Works in Both MySQL and PostgreSQL

Write a SQL query to retrieve all employees whose salary is greater than the average salary, ensuring compatibility with both MySQL and PostgreSQL.

Solution:

-- Retrieve employees with salaries above the average.
SELECT EmployeeID, Name, Salary
FROM Employees
WHERE Salary > (SELECT AVG(Salary) FROM Employees);

Explanation:

• Purpose of the Query :
• The goal is to demonstrate how to write a query that works across multiple database systems (MySQL and PostgreSQL).
• Key Components :
• SELECT: Retrieves employee details.
• WHERE Salary > (SELECT AVG(Salary)): Filters employees with salaries above the average.
• Why Ensure Cross-Platform Compatibility?:
• Cross-platform queries simplify migration and ensure consistent behavior across environments.
• They reduce the need for rewriting queries when switching database systems.
• Real-World Application :
• In multi-database environments, cross-platform queries support seamless integration.

Notes on the issue:

• Avoid using database-specific syntax or functions (e.g., TOP in SQL Server or LIMIT in MySQL/PostgreSQL).
• Use ANSI SQL standards for maximum compatibility.
• Important Considerations:
• Test queries on all target platforms to ensure consistent results.

For more Practice: Solve these Related Problems:

• Write a SQL query to retrieve all customers whose order count is greater than the average order count, ensuring compatibility with both MySQL and PostgreSQL.
• Write a SQL query to find all products with a price higher than the average price, ensuring compatibility with both MySQL and PostgreSQL.
• Write a SQL query to retrieve all students whose score is greater than the average score, ensuring compatibility with both MySQL and PostgreSQL.
• Write a SQL query to find all departments with a budget greater than the average budget, ensuring compatibility with both MySQL and PostgreSQL.

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