Why should you care?

HR needs “who manages Priya?” when ManagerId points at another Employees.EmployeeId.

See it live — copy this example

Run in SQL Server Management Studio (SSMS) or Azure Data Studio.

USE DataVerse;
IF OBJECT_ID(N'dbo.Employees', N'U') IS NOT NULL DROP TABLE dbo.Employees;
CREATE TABLE dbo.Employees (
    EmployeeId INT PRIMARY KEY,
    FullName NVARCHAR(100) NOT NULL,
    ManagerId INT NULL
);
INSERT INTO dbo.Employees VALUES
 (1, N'Anita Rao', NULL),
 (2, N'Priya Shah', 1),
 (3, N'Rohan Das', 1);
SELECT e.FullName AS Employee, m.FullName AS Manager
FROM dbo.Employees AS e
LEFT JOIN dbo.Employees AS m ON m.EmployeeId = e.ManagerId;

What happened?

• Alias e is the employee; alias m is the manager row from the same table.
• LEFT JOIN keeps Anita who has no manager.

Practice next

1. Create Employees and run the self join.
2. Add another level (Rohan manages someone) and extend the query.
3. Find employees whose manager name is Anita.
4. Show ManagerId and manager email if you add Email.
5. Count direct reports with GROUP BY ManagerId.

Remember

Self join = one table, two roles. Aliases are mandatory for clarity. Common for org charts and bill-of-materials.

Org chart in DataVerse HR

HR app resolves manager names via self join on Employees.

Outcome: Directory page shows Employee — Manager pairs.