Group_concat () usage in MySQL

Basic syntax: Group_concat ([DISTINCT] field to connect [order by sort field Asc/desc] [Separator ' delimiter '])

Initial data:

　　Group by name, print money on one line, default ', ' delimited:

Select AA. ' Name ' name, Group_concat (money) money from the AA GROUP by AA. ' Name '

　　　　

　　Group by name, print money on one line, separated by '; '

Select AA. ' Name ' name, Group_concat (Money separator '; ') money from the AA GROUP by AA. ' Name '

　　　　

　　Group by name, remove redundant money, separate with '; '

Select AA. ' Name ' name, Group_concat (DISTINCT money separator '; ') money from the AA GROUP by AA. ' Name '

　　　　

parameter setting and restriction description
1. View settings on the server

Mysql> Show variables like '%group_concat% '; +----------------------+-------+ | Variable_name        |　　　　　　Value | +----------------------+-------+ | Group_concat_max_len |　　　　　　1024x768  | +----------------------+-------+ 1 row in Set (0.00 sec)

The value of the above setting indicates that the default length is currently 1KB

2. Changing parameter values
Method One: Modify the parameters in the configuration file, add Group_concat_max_len = 10240
Method Two: Implemented in session, global or current session
SET GLOBAL group_concat_max_len=10240;
SET SESSION group_concat_max_len=10240;

Group_concat () usage in MySQL