What are some examples of SQL queries?

What are some examples of SQL queries I can use?

Sure! Here are a few examples of SQL queries:

1. SELECT * FROM users; - Retrieves all records from the users table.
2. INSERT INTO orders (user_id, product_id) VALUES (1, 2); - Adds a new order.
3. UPDATE products SET price = 19.99 WHERE id = 1; - Updates the price of a product.
4. DELETE FROM sessions WHERE last_active < '2023-01-01'; - Deletes old session records.

Can you explain what each of these queries does?

Of course!

1. SELECT * FROM users; fetches all columns for every user in the users table.
2. INSERT INTO orders (user_id, product_id) VALUES (1, 2); adds a new entry in the orders table for user 1 purchasing product 2.
3. UPDATE products SET price = 19.99 WHERE id = 1; changes the price of the product with ID 1 to $19.99.
4. DELETE FROM sessions WHERE last_active < '2023-01-01'; removes sessions that haven't been active since before January 1, 2023.

What if I want to filter results in a SELECT query?

You can use the WHERE clause to filter results. For example, SELECT * FROM users WHERE age > 18; retrieves users older than 18.