SQL Tutorial

SQL Introduction SQL Aggregate Functions SQL Aliases SQL And SQL Any All SQL Avg SQL Between SQL Case SQL Comments SQL Count SQL Delete SQL Distinct SQL Exists SQL GROUP BY SQL Having SQL In SQL INSERT INTO SQL Is Not Null SQL Join SQL Full Outer Join SQL Inner Join SQL Left Join SQL Right Join SQL Self Join SQL Like SQL Min Max SQL NOT Operator SQL Null SQL Operators SQL OR operator SQL ORDER BY SQL Select SQL Select Into SQL Top Limit Fetch SQL Stored Procedures SQL Sum SQL Union SQL Update SQL Where SQL Wildcards

SQL Database

SQL Alter Table SQL Auto increment SQL Backup Database SQL Check SQL Constraints SQL Create View SQL Create Database SQL Create Table SQL Data types SQL Dates SQL Default Constraint SQL Drop Database SQL Drop Table SQL Foreign Key SQL Hosting SQL Index SQL injections SQL Not NULL SQL PrimaryKey SQL Unique SQL Views

SQL Where

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