Shulou(Shulou.com)06/02 Report--

Today, I will talk to you about how to use the group_concat function in MySQL. Many people may not know much about it. In order to make you understand better, the editor has summarized the following for you. I hope you can get something according to this article.

Example

1. Single-column multi-row merge single-row single-column display

Select group_concat (name) as name from student where classId = 1

The execution result is as follows:

two。 Multi-column splicing, multi-column and multi-row values are merged into a single row and single column display

Select group_concat (name,sex) as name from student where classId = 1

The execution result is as follows:

3. Value sort splicing

Select group_concat (name order by id desc) as name from student where classId = 1

‍

Function dependent configuration

1.group_concat length:

The default maximum length of group_concat is 1024, which exceeds 1024 characters before interception.

two。 Query group_concat length SQL

Show variables like 'group_concat_max_len'

3. Change group_concat length configuration

① modifies MYSQL's configuration file my.ini (mysql service needs to be restarted):

Group_concat_max_len = 2048

② execution statement

SET GLOBAL group_concat_max_len=1024000;SET SESSION group_concat_max_len=1024000;, after reading the above, do you have any further understanding of how to use the group_concat function in MySQL? If you want to know more knowledge or related content, please follow the industry information channel, thank you for your support.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.