Add multi tables view describe.

ch03:复杂一点的查询.md

@@ -112,16 +112,19 @@ INSERT INTO shop_product (shop_id, shop_name, product_id, quantity) VALUES ('000
 INSERT INTO shop_product (shop_id, shop_name, product_id, quantity) VALUES ('000D',	'福冈',		'0001',	100);
 ```
 
-我们在product表和shop_product表的基础上创建视图。
+**创建多表视图和核心语句和多表关联查询语句相同，只不过多了 `CREATE VIEW VIEW_NAME AS`。**
+
+下面，我们在 product 表和 shop_product 表的基础上创建视图。
 
 ```sql
 CREATE VIEW view_shop_product(product_type, sale_price, shop_name)
 AS
 SELECT product_type, sale_price, shop_name
-  FROM product,
-       shop_product
+  FROM product
+  JOIN shop_product
  WHERE product.product_id = shop_product.product_id;
 ```
+
 创建的视图如下图所示
 
 ![图片](./img/ch03/ch03.04view4.png)