SQL CODES

SELECT * FROM table_name;

SELECT DISTINCT Country FROM Customers;

SELECT * FROM Customers WHERE Country='Mexico';


===== AND, OR, NOT =====

SELECT * FROM Customers
WHERE Country='Germany' AND City='Berlin';

SELECT * FROM Customers
WHERE City='Berlin' OR City='München';

SELECT * FROM Customers
WHERE NOT Country='Germany';



===== ORDER BY =====

SELECT * FROM Customers
ORDER BY Country;

SELECT * FROM Customers
ORDER BY Country DESC;

SELECT * FROM Customers
ORDER BY Country ASC, CustomerName DESC;



===== INSERT INTO =====

INSERT INTO Customers (CustomerName, ContactName, Address, City, PostalCode, Country)
VALUES ('Cardinal', 'Tom B. Erichsen', 'Skagen 21', 'Stavanger', '4006', 'Norway');


===== NULL =====

SELECT CustomerName, ContactName, Address
FROM Customers
WHERE Address IS NULL;

SELECT CustomerName, ContactName, Address
FROM Customers
WHERE Address IS NOT NULL;



===== UPDATE =====

UPDATE Customers
SET ContactName = 'Alfred Schmidt', City= 'Frankfurt'
WHERE CustomerID = 1;

Be careful when updating records. If you omit the WHERE clause, ALL records will be updated!



===== DELETE =====

DELETE FROM Customers WHERE CustomerName='Alfreds Futterkiste';

Be careful when deleting records in a table! Notice the WHERE clause in the DELETE statement. The WHERE clause specifies which record(s) should be deleted. If you omit the WHERE clause, all records in the table will be deleted!


===== SELECT TOP =====

SELECT TOP 3 * FROM Customers;
SELECT TOP 50 PERCENT * FROM Customers;
SELECT MIN(Price) AS SmallestPrice
FROM Products;