SQL - lesson 4 | HackIndia Skills | HackIndia

SQL - lesson 4 | HackIndia Skills | HackIndia

-- List orders with buyer details
SELECT
  orders.id AS order_id,
  orders.total_rupees,
  orders.status,
  users.name AS buyer_name,
  users.email AS buyer_email
FROM orders
INNER JOIN users
  ON orders.user_id = users.id
ORDER BY orders.id DESC;

Example

LEFT JOIN for missing data

Use LEFT JOIN when you want every row from the left table, even if the joined table has no match. This helps with optional data.

For example, not every student profile may have a submitted project yet. A LEFT JOIN can still show all students.

-- Show all students, with project title if submitted
SELECT
  students.id AS student_id,
  students.name,
  projects.title AS project_title
FROM students
LEFT JOIN projects
  ON projects.student_id = students.id
ORDER BY students.name;