Lesson 13 - Databases

Single-Table SELECT Statements

• SELECT * FROM CUSTOMERS;
• SELECT CustomerID, FirstName, LastName FROM CUSTOMERS;
• SELECT * FROM CUSTOMERS WHERE LastName = 'Smith';
• SELECT * FROM CUSTOMERS ORDER BY LastName ASC;
• SELECT * FROM PRODUCTS WHERE Price > 50;
• SELECT COUNT(*) FROM ORDERS;

INSERT, UPDATE, and DELETE Statements

• INSERT INTO CUSTOMERS (FirstName, LastName, Email) VALUES ('Jane', 'Doe', 'jane@example.com');
• INSERT INTO PRODUCTS (ProductName, Price, Stock) VALUES ('Widget', 9.99, 100);
• UPDATE CUSTOMERS SET Email = 'new@example.com' WHERE CustomerID = 1;
• UPDATE PRODUCTS SET Price = 12.99 WHERE ProductName = 'Widget';
• DELETE FROM CUSTOMERS WHERE CustomerID = 5;
• DELETE FROM ORDERS WHERE OrderDate < '2024-01-01';

What I Learned

In this lesson I learned about databases and how to use SQL to work with them. SQL lets you get information out of a database using SELECT statements. You can also add new records with INSERT, change existing ones with UPDATE, and remove them with DELETE. I also learned that it is important to use a WHERE clause with UPDATE and DELETE so you don't accidentally change all the rows in a table. I can use this in the future if I build a website that needs to store information like user accounts or a list of products.