Mybatis用SQL做自连表查询

POJO
package com.lpc.labbackend.entity;

import java.util.List;

public class Menu {
private Integer id;
private String description;
private String path;
private List

childMenus;

//省略构造函数、getter、setter

}
5 Mybatis的mapper.xml











id, description, path

    select
    
    from menu
    where parent_menu_id is null



    select
    
    from menu
    where menu.parent_menu_id = #{id}

resultMap标签中用一个collection标签表示Java里的List，ofType属性表示这个集合的类型。这个List是通过select属性使用了一个查询语句获取数据，column属性是这个查询语句的查询条件。

6 前台接收到的数据
0: {id: 1, icon: "el-icon-user-solid", description: "账户设置", path: null,…}
id: 1
icon: "el-icon-user-solid"
description: "账户设置"
path: null
childMenus: [{id: 5, icon: null, description: "所有账户", path: "users", childMenus: null}]
0: {id: 5, icon: null, description: "所有账户", path: "users", childMenus: null}
id: 5
icon: null
description: "所有账户"
path: "users"
childMenus: null
1: {id: 2, icon: "el-icon-s-data", description: "信息统计", path: null,…}
2: {id: 3, icon: "el-icon-s-check", description: "申请批准", path: null,…}
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