Using SQL for Data Manipulation, Queries, and Transactions

Intermediate

💬 SQL Basics in PostgreSQL

SQL is the cornerstone of interacting with PostgreSQL, enabling:

  • 📥 Data insertion
  • 🔍 Retrieval
  • ✏️ Updating
  • ❌ Deletion

➕ INSERT Example

INSERT INTO books (title, author_id) VALUES ('Deep Learning', 1);

🔍 SELECT with Conditions

SELECT * FROM books WHERE author_id = 1;

🔄 Transactions for Data Consistency

BEGIN;
UPDATE accounts SET balance = balance - 100 WHERE account_id = 1;
UPDATE accounts SET balance = balance + 100 WHERE account_id = 2;
COMMIT;

✅ Use BEGIN, COMMIT, and ROLLBACK to group operations atomically.

🛡️ This guarantees all operations within a transaction either complete successfully or not at all, maintaining data integrity.