Filtering and Sorting data using SQL statements

 Filtering & Sorting Data using SQL 

 

Once you know the basics (SELECT, FROM, WHERE), filtering and sorting helps you get the exact rows from tables .

 1. Filtering with Conditions (AND, OR, NOT) 

- Use WHERE to filter rows.

- Combine with logical operators: 

  • AND: all conditions true 

  • OR: any condition true 

  • NOT: negate condition 

-- All conditions true (AND)

SELECT * FROM employees

WHERE department = 'Sales'   AND salary > 50000;

-- Any condition true (OR)

SELECT * FROM employees

WHERE department = 'Sales'    OR department = 'Marketing';

-- Negate condition (NOT)

SELECT * FROM employees

WHERE NOT department = 'HR';

 

2.Pattern Matching with LIKE 

- % = any sequence, _ = single char 

  • Names starting with 'J' 

  • Names with 4 letters starting with 'J' 

-- Names starting with 'J'

SELECT * FROM customers

WHERE name LIKE 'J%';

-- Names with four letters starting with 'J'

SELECT * FROM customers

WHERE name LIKE 'J___';

 

3. Filtering with IN 

- Check if value matches any in list 

  SELECT * FROM products WHERE category IN ('Electronics', 'Furniture'); 

 

4. Range Checking with BETWEEN 

- Filter values in a range (inclusive) 

  SELECT * FROM orders WHERE order_date BETWEEN '2023-01-01' AND '2023-12-31'; 

 

5. Checking for NULL Values 

- Find NULL: 

  SELECT * FROM employees WHERE manager_id IS NULL;

- Find NOT NULL: 

  SELECT * FROM employees WHERE manager_id IS NOT NULL; 

 

6. Sorting with ORDER BY 

- Ascending (default): 

  SELECT * FROM employees ORDER BY salary; 

- Descending: 

  SELECT * FROM employees ORDER BY salary DESC; 

- Multiple columns: 

  SELECT * FROM employees ORDER BY department, salary DESC;