SQL DISTINCT Tutorial

Example Table

We will use the following table named employees for our examples:

    CREATE TABLE employees (
        employee_id INT PRIMARY KEY,
        employee_name VARCHAR(50),
        department VARCHAR(50),
        salary DECIMAL(10, 2)
    );
    
    INSERT INTO employees (employee_id, employee_name, department, salary) VALUES
    (1, 'John Doe', 'HR', 50000.00),
    (2, 'Jane Smith', 'Finance', 60000.00),
    (3, 'Sam Brown', 'IT', 70000.00),
    (4, 'Nancy White', 'HR', 55000.00),
    (5, 'Mike Green', 'Finance', 65000.00);
    

employee_id	employee_name	department	salary
1	John Doe	HR	50000.00
2	Jane Smith	Finance	60000.00
3	Sam Brown	IT	70000.00
4	Nancy White	HR	55000.00
5	Mike Green	Finance	65000.00

Using SQL DISTINCT

The SQL DISTINCT keyword is used to return only distinct (different) values.

Selecting Distinct Values from a Column

To select distinct values from a column, use SELECT DISTINCT column_name FROM table_name:

    SELECT DISTINCT department
    FROM employees;
    

Result:

department	HR
	Finance
	IT

Selecting Distinct Values from Multiple Columns

To select distinct values from multiple columns, use SELECT DISTINCT column1, column2 FROM table_name:

    SELECT DISTINCT department, salary
    FROM employees;
    

Result:

department	HR
salary	50000.00
department	Finance
salary	60000.00
department	IT
salary	70000.00
department	HR
salary	55000.00
department	Finance
salary	65000.00

Counting Distinct Values

To count the number of distinct values in a column, use SELECT COUNT(DISTINCT column_name) FROM table_name:

    SELECT COUNT(DISTINCT department) AS unique_departments
    FROM employees;
    

Result:

unique_departments	3