转载：SQL表格連接 (Join)

使用表格连接来同时查询两个及以上数量的表。

http://www.1keydata.com/tw/sql/sqljoins.html

亮点：

SELECT A1.region_name REGION, SUM(A2.Sales) SALES
FROM Geography A1, Store_Information A2
WHERE A1.store_name = A2.store_name
GROUP BY A1.region_name

結果 :

REGION	SALES
East	$700
West	$2050