mysql GROUP_CONCAT () function of the maximum length of the pit

Function values ​​may be the same field in multiple records GROUP_CONCAT (), return spliced ​​into a record. But by default, the maximum length of the stitching is limited, resulting in incomplete results.

You can use sql query maximum length:

show variables like 'group_concat_max_len';

　To modify the maximum length:

SET GLOBAL group_concat_max_len = 4294967295;
SET SESSION group_concat_max_len = 4294967295;

Reference Address: https://blog.csdn.net/zs345048102/article/details/81237807