Data Archive

View Use Case

View Use Case

Scenario

A company wants to generate monthly performance reports for its employees. The performance data is spread across multiple tables, including employees, departments, and performance_reviews. Instead of writing complex queries every time a report is needed, the company can create a view that simplifies data retrieval.

Step 1: Define the Tables

Assume we have the following tables:

  • employees: Contains employee details.

    • employee_id
    • name
    • department_id

  • departments: Contains department details.

    • department_id
    • department_name

  • performance_reviews: Contains performance review data.

    • review_id
    • employee_id
    • review_score
    • review_date

Step 2: Create a View

To simplify the reporting process, we create a view that joins these tables and aggregates the performance scores:

CREATE VIEW employee_performance AS
SELECT 
    e.employee_id,
    e.name,
    d.department_name,
    AVG(pr.review_score) AS average_score
FROM 
    employees e
JOIN 
    departments d ON e.department_id = d.department_id
JOIN 
    performance_reviews pr ON e.employee_id = pr.employee_id
GROUP BY 
    e.employee_id, e.name, d.department_name;

Step 3: Query the View

Now, whenever the HR department needs to generate a performance report, they can simply query the employee_performance view:

SELECT * FROM employee_performance WHERE average_score >= 4.0;

This query retrieves all employees with an average performance score of 4.0 or higher, making it easy to identify top performers.

Benefits of Using Views in This Use Case

  1. Simplification: The view encapsulates complex joins and aggregations, allowing HR to retrieve performance data without needing to understand the underlying table structure.

  2. Reusability: The view can be reused for different reports, such as quarterly reviews or department-specific performance assessments.

  3. Maintainability: If the logic for calculating performance scores changes, the HR team only needs to update the view definition, not every individual query.

  4. Data Consistency: All reports generated from the view will be consistent, as they rely on the same underlying logic for calculating average scores.

  5. Security: If sensitive employee data needs to be protected, the view can be designed to exclude certain columns, ensuring that only necessary information is accessible.

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