Advanced SQL Projects

You have now reached the Advanced SQL stage.

In this lesson, we work through real-world advanced SQL projects that combine performance, analytics, and database engineering concepts.

These projects reflect how SQL is used in professional environments.

Project 1: Employee Performance Analytics

Scenario: A company wants to analyze employee salaries within each department.

Requirements:

• Rank employees by salary within departments
• Show department average salary
• Preserve individual employee records

Solution

SELECT name,
       department,
       salary,
       RANK() OVER (
         PARTITION BY department
         ORDER BY salary DESC
       ) AS salary_rank,
       AVG(salary) OVER (
         PARTITION BY department
       ) AS dept_avg_salary
FROM employees;
  

This project uses window functions to perform analytics without grouping rows.

Project 2: Organizational Hierarchy

Scenario: Generate a full organizational chart from a manager–employee relationship.

Requirements:

• Show all levels of hierarchy
• Include reporting depth

Solution

WITH RECURSIVE org_chart AS (
  SELECT id, name, manager_id, 1 AS level
  FROM employees
  WHERE manager_id IS NULL

  UNION ALL

  SELECT e.id, e.name, e.manager_id, oc.level + 1
  FROM employees e
  JOIN org_chart oc
  ON e.manager_id = oc.id
)
SELECT * FROM org_chart;
  

Recursive queries allow unlimited hierarchy depth.

Project 3: JSON-Based User Profiles

Scenario: Store and query flexible user profile data.

Requirements:

• Store preferences as JSON
• Query users by JSON attributes

Solution

SELECT id,
       profile->>'$.city' AS city,
       profile->>'$.role' AS role
FROM users
WHERE profile->>'$.role' = 'Admin';
  

This approach supports evolving schemas.

Project 4: Dynamic Reporting Query

Scenario: Build a report where the filter column changes dynamically.

Requirements:

• Dynamic column selection
• Safe execution

Solution

SET @column = 'department_id';
SET @value = 1;

SET @sql = CONCAT(
  'SELECT name, salary FROM employees WHERE ',
  @column, ' = ', @value
);

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
  

Dynamic SQL enables flexible reporting systems.

Project 5: Performance Optimization

Scenario: Improve slow department-based queries.

Steps:

• Analyze query execution plan
• Add appropriate index

Solution

EXPLAIN
SELECT name, salary
FROM employees
WHERE department_id = 2;

CREATE INDEX idx_dept
ON employees(department_id);
  

Indexes dramatically reduce execution time.

Concepts Applied in This Lesson

• Window functions
• Recursive queries
• JSON data handling
• Dynamic SQL
• Index tuning

Why These Projects Matter

These projects simulate:

• Enterprise analytics
• HR and reporting systems
• Flexible application backends
• Performance-critical environments

Mastering these patterns prepares you for real SQL engineering roles.

What’s Next?

In the final lesson, we will complete a Mini SQL Project that combines everything learned from beginner to advanced levels.