SQL WHERE Clause Tutorial

Example Table

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

    CREATE TABLE employees (
        employee_id INT PRIMARY KEY,
        name VARCHAR(50),
        department VARCHAR(50),
        salary DECIMAL(10, 2)
    );

    INSERT INTO employees (employee_id, name, department, salary) VALUES
    (1, 'Alice', 'HR', 50000.00),
    (2, 'Bob', 'IT', 60000.00),
    (3, 'Charlie', 'Finance', 55000.00);
    

Employees Table

employee_id	name	department	salary
1	Alice	HR	50000.00
2	Bob	IT	60000.00
3	Charlie	Finance	55000.00

Using the SQL WHERE Clause

The SQL WHERE clause is used to filter records.

Example: Filtering by Department

To select employees from the IT department:

    SELECT * FROM employees
    WHERE department = 'IT';
    

Result:

Query	SELECT * FROM employees WHERE department = 'IT';
Result	employee_id: 2, name: Bob, department: IT, salary: 60000.00

Example: Filtering by Salary

To select employees with a salary greater than 55000.00:

    SELECT * FROM employees
    WHERE salary > 55000.00;
    

Result:

Query	SELECT * FROM employees WHERE salary > 55000.00;
Result	employee_id: 2, name: Bob, department: IT, salary: 60000.00

Example: Combining Conditions

To select employees from the HR department with a salary less than 60000.00:

    SELECT * FROM employees
    WHERE department = 'HR' AND salary < 60000.00;
    

Result:

Query	SELECT * FROM employees WHERE department = 'HR' AND salary < 60000.00;
Result	employee_id: 1, name: Alice, department: HR, salary: 50000.00