Mybatis查询树状结构的菜单

通过mybatis查询树状结构的数据，超级实用。
1，定义实体类

public class Menu  {
    private String id;  //主键
    private String pid; //父级主键
    private String name;  //菜单名称
    private List<Menu> children;  //子菜单集合
}

2，写mapper.xml

    
    
             
             
             
        
    

    
    
        SELECT * FROM menu WHERE  pid ='' OR pid is NULL  OR pid = 'ROOT' OR pid = 'root' ORDER BY `create_time` ASC
    
   
   
    
        SELECT *  FROM   menu WHERE    pid = #{arg0}