What is the MySQL column to row function

mysql What does the column to row function mean

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stay mysql in , The column to row function is “group_concat()” function ; This function is used to merge non empty column values according to grouping conditions and finally return , If there is a null value, the returned result is null , The grammar is “select group_concat(name  separator ';') Name from Table name ;”.

The operating environment of this tutorial ：windows10 System 、mysql8.0.22 edition 、Dell G3 The computer .

mysql What is the column to row function

GROUP_CONCAT(expr) This function combines the non empty column values according to the grouping conditions and finally returns . If there is a null value , Then return to empty

stay MySQL in , How to turn a column into a row ？ For example, a commodity will belong to multiple categories ( For example, Huawei mobile phones can be classified as mobile phones , It can also be digital classification ), How to show all categories of this commodity in one piece of data .

The idea is simple , adopt MySQL function group_concat Can solve .

Create test table ：

create table test.test_mysql_liezhuanhang (id         bigint auto_increment comment ' Primary key ',name       varchar(100),age        int(5),primary key (id))engine=innodb default charset=utf8mb4 comment=' The test table '

Import test data ：

insert into test.test_mysql_liezhuanhang (name, age) values (' Li Wei ', 18), (' Li Wei ', 19), (' Li Wei ', 18), (' Li Bai ', 20), (' Li Bai ', 20), (' Li Bai ', 19);

Show all names , Divide by semicolon , Default to , Division

select group_concat(name  separator ';') concat  from test.test_mysql_liezhuanhang ;

Show all names , And duplicate the same name

select group_concat(distinct name) concat  from test.test_mysql_liezhuanhang ;

Show all ages , De duplication and sort in ascending order of age

select group_concat(distinct age order by age) concat  from test.test_mysql_liezhuanhang ;

Thank you for reading , That's all “mysql What does the column to row function mean ” Content. , After learning this article , I'm sure you're right mysql We have a deeper understanding of what the column to row function refers to , The specific use needs to be verified by practice . This is billion speed cloud , Xiaobian will push you articles with more relevant knowledge points , Welcome to your attention ！