[] Mysql Mysql function returns the value of group_concat length limit

　　group_concat function returns the maximum length will be truncated group_concat_max_len system variables given, the default value of the variable 1024.

      group_concat_max_len may be set higher (the maximum effective length of the return value will be limited max_allowed_packet value).

　　Setting Syntax: the SET [the GLOBAL | the SESSION] group_concat_max_len = val; where val is an unsigned integer type, represents the number of bytes

　

1) Find the length of the current database

show variables like 'group_concat_max_len' 

2) Set the length of current session group_concat other session connections are unaffected

SET SESSION group_concat_max_len = 10240;

3) set the global group_concat length, the current session is not affected, it is necessary to disconnect and reconnect to take effect

SET GLOBAL group_concat_max_len = 10240