摘要：
嵌套集模型（The Nested Set Model）示意图上图表现了数据新的层级关系，关系表和数据如下CREATE TABLE nested_category (category_id INT AUTO_INCREMENT PRIMARY KEY,name VARCHAR(20) NOT NULL,lft INT NOT NULL,rgt INT NOT NULL);INSERT INTO nested_categoryVALUES(1,'ELECTRONICS',1,20),(2,'TELEVISIONS',2,9),(3,'TUBE',3, 阅读全文
