1.4 分类实现 - 自连接查询子分类

在 navicat 工具中新建查询

SELECT
    f.id AS id,
    f.`name` AS `name`,
    f.type AS type,
    f.father_id AS fatherId,
    c.id AS subId,
    c.`name` AS subName,
    c.type AS subType,
    c.father_id AS subFatherId 
FROM
    category f
    LEFT JOIN category c ON f.id = c.father_id 
WHERE
    f.father_id = 1