Bits of .NET

SELECT * feels convenient…
…but costs you RAM, CPU, network IO, and index usage.

❌ Why SELECT * Is Dangerous

• 🧱 Prevents covering index usage

• 🚚 Sends unnecessary columns over network

• 🔄 Breaks when columns change

• 🐢 Slows down joins & scans

-- ❌ Bad
SELECT * FROM Orders;

-- ✔ Good
SELECT Id, OrderDate, Amount FROM Orders;

💡 Bonus

Use covering indexes to turn scans into instant index seeks.