INSERT

Add new rows to a table:

```sql

-- Insert one row (specifying columns)

INSERT INTO users (name, email, plan)

VALUES ('Alice', 'alice@example.com', 'free');

-- Insert without column list (must match table order)

INSERT INTO users VALUES (1, 'Alice', 'alice@example.com', 'free');

-- Insert multiple rows

INSERT INTO products (name, price) VALUES

('Widget', 9.99),

('Gadget', 49.99),

('Thingamajig', 24.99);

```

---

INSERT OR IGNORE / ON CONFLICT

Handle duplicate inserts gracefully:

```sql

-- SQLite: ignore if the row already exists

INSERT OR IGNORE INTO users (email, name) VALUES ('alice@example.com', 'Alice');

-- PostgreSQL: upsert pattern

INSERT INTO users (email, name) VALUES ('alice@example.com', 'Alice')

ON CONFLICT (email) DO UPDATE SET name = EXCLUDED.name;

```

---

UPDATE

Change existing rows:

```sql

-- Always include WHERE — without it, every row is updated!

UPDATE users SET plan = 'pro' WHERE id = 42;

-- Update multiple columns

UPDATE products

SET price = price * 1.1, updated_at = CURRENT_TIMESTAMP

WHERE category = 'electronics';

```

---

DELETE

Remove rows:

```sql

-- Delete specific rows

DELETE FROM sessions WHERE expires_at < CURRENT_TIMESTAMP;

-- Delete all rows (keeps table structure)

DELETE FROM temp_data;

```

---

Safety Rules

1. **Always test with SELECT first** — run a `SELECT WHERE...` to confirm which rows you'll affect before running `UPDATE`/`DELETE`

2. **Use transactions** — wrap destructive operations in `BEGIN`/`COMMIT`

3. **Never run UPDATE/DELETE without WHERE** unless you mean to affect every row

---

What's Next?

Next: **Subqueries** — use the result of one query inside another.