About MySQL group_ What concat has to say

mysql in ,group_concat Function will group by The resulting values in the same group are connected , Returns a string result .

When too much data is queried ,group_concat Default value exceeded 1024 Characters , If it exceeds, it will be truncated , Lead to group_concat Incomplete data found .

well , This is an easily overlooked pit .

solution 1：
https://www.freesion.com/article/2975170859/
http://www.javashuo.com/article/p-zqzeqcby-ws.html

solution 2：
no need group_concat, Use alternatives , For example, check the grouping value first, and then traverse the processing data