Mysql implementation merges the same ID corresponding to multiple data method _mysql

This article illustrates the MySQL implementation method that merges multiple data with the same ID. Share to everyone for your reference, specific as follows:

Such as:

CREATE TABLE ' c_classuser_tab ' (
 ' Id ' int () NOT NULL auto_increment,
 ' Classid ' int (one) DEFAULT null,
 ' Username ' varchar (MB) default null,
 ' studentid ' varchar (m) default null,
 ' College ' varchar (MB) default null ,
 ' Department ' varchar (MB) default null,
 ' Email ' varchar default NULL,
 ' Phone ' varchar ' default NULL, '
 Status ' int (one) default null,
 ' Remark1 ' varchar (MB) default null,
 ' REMARK2 ' varchar (m) default NULL,
 ' REMARK3 ' varchar (MB) default null,
 ' activatetime ' datetime default NULL,
 ' Jointime ' datetime Default NULL,
 ' UserID ' int (one) default null,
 ' usertype ' int (one) default null,
 PRIMARY KEY (' Id '),
 Key ' C_classuser_tab_index ' (' StudentID '),
 key ' Idx_classuser_complex ' (' Classid ', ' UserID ')
engine= MyISAM auto_increment=31091 DEFAULT Charset=utf8;

Teachers with the same ID have multiple substitute classes that combine them,

Teacher Substitute class

12, Class 1, Class 2.

Copy Code code as follows:

Select Username, Group_concat (Remark1, ') as classes from C_classuser_tab where userid= * and usertype=*

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I hope this article will help you with the MySQL database meter.