行转列:
GROUP_CONCAT(spec_id ORDER BY spec_id SEPARATOR ',')
ORDER BY :排序
SEPARATOR : 分隔关键字
CONCAT():字段拼接字符
SELECT type_id,CONCAT('[',GROUP_CONCAT(spec_id ORDER BY spec_id SEPARATOR ','),']') AS spec_ids FROM ( SELECT spec_id, type_id FROM goods_type_spec WHERE type_id IN (SELECT type_id FROM goods_type) ORDER BY type_id )a GROUP BY type_id
![](https://img2018.cnblogs.com/blog/1180018/201902/1180018-20190227143607643-1099991887.png)