Employee Data Analysis with PostgreSQL

Designed and queried a relational database to analyze employee records for a fictional company. Created a normalized schema, loaded data from CSV files, and used complex SQL queries to explore salary trends, department structures, and manager assignments.

Tools & Technologies Used

• PostgreSQL
• SQL
• ERD (Entity Relationship Diagram)
• Jupyter Notebooks

File Structure

.
├── EmployeeSQL_schemata.sql         # Database schema creation
├── EmployeeSQL_queries.sql          # SQL queries and analysis
├── EmployeeSQL_ERD.png              # Entity Relationship Diagram
├── Resources/
│   ├── employees.csv                # Employee records
│   ├── salaries.csv                 # Salary data
│   ├── dept_emp.csv                 # Department-employee mapping
│   ├── dept_manager.csv             # Department-manager mapping
│   ├── departments.csv              # Department details
│   └── titles.csv                   # Employee titles

Skills Demonstrated

• Relational database design and schema creation
• SQL querying with joins, aggregations, and subqueries
• Data modeling with ERDs
• Loading and cleaning large datasets into PostgreSQL
• Analyzing salary and department trends

Key Findings

• Analyzed 300,000+ employee records across multiple tables.
• Identified employees with the highest salaries by department.
• Queried average salary trends for employees by title.
• Explored relationships between managers, departments, and tenure.
• Designed and implemented an optimized relational database structure.