UNION operator in SQL

 

Cú pháp:

SELECT column_name(s) FROM table1
UNION
SELECT column_name(s) FROM table2;

SELECT column_name(s) FROM table1
UNION ALL
SELECT column_name(s) FROM table2;

Ví dụ: 

SELECT City FROM Customers
UNION
SELECT City FROM Suppliers
ORDER BY City;

SELECT City FROM Customers
UNION ALL
SELECT City FROM Suppliers
ORDER BY City;