UPDATE Data Patterns

-- Update single column
UPDATE users 
SET status = 'active'
WHERE id = 1;

-- Update multiple columns
UPDATE users 
SET 
  status = 'active',
  verified = true,
  updated_at = NOW()
WHERE id = 1;

-- Update with condition
UPDATE orders 
SET status = 'completed'
WHERE payment_status = 'paid' 
  AND shipped_at IS NOT NULL;

-- Update from calculation
UPDATE products 
SET discounted_price = price * 0.9
WHERE category = 'electronics';

-- Update with JOIN (PostgreSQL/MySQL)
UPDATE users u
INNER JOIN orders o ON u.id = o.user_id
SET u.last_order_date = o.created_at
WHERE o.id IN (
  SELECT MAX(id) 
  FROM orders 
  GROUP BY user_id
);

-- Conditional update with CASE
UPDATE users
SET status = CASE
  WHEN last_login > NOW() - INTERVAL '30 days' THEN 'active'
  WHEN last_login > NOW() - INTERVAL '90 days' THEN 'inactive'
  ELSE 'dormant'
END;

-- Update and return (PostgreSQL)
UPDATE users 
SET status = 'active'
WHERE id = 1
RETURNING *;

-- Increment counter
UPDATE products 
SET view_count = view_count + 1
WHERE id = 123;

-- Update all rows (BE CAREFUL!)
UPDATE users 
SET notification_enabled = true;

-- Safe update with LIMIT (MySQL)
UPDATE users 
SET status = 'migrated'
WHERE status = 'legacy'
LIMIT 100;