The Group_concat function in MySQL displays multiple data as a single piece of data

There is such a demand
1: Class table
ID class_name
2: Student Table
ID Name class_id

If we were to check all the classes and the students in each class, you would have thought of that:

The code is as follows	Copy Code
SELECT banji.*, User.Name From ' Banji ' Left JOIN user On Banji.id=user. ' Class ' where banji.id=2

So the number of results we get is the same as the number of students, and I want to get a piece of data, and this data contains all the students, you can write:

The code is as follows	Copy Code
SELECT banji.*, Group_concat (user.name) as names From ' Banji ' Left JOIN user On Banji.id=user. ' Class ' where banji.id=2 This results in a single result, and the result contains all the student name, ID class_name Names

22 Lisi,zhaoliu,liu, Waiter, Xiaoming, Xiao Zhang

You can also customize the separator:

code is as follows	copy code
select banji.*, Group_concat (user.name SEPARATOR "|") as names from ' Banji ' Left join user on Banji.id=user. ' Class ' where banji.id=2 Results: id  class_name  names 2  two   lisi|zhaoliu|liu| small two |xiaoming| Small Zhang