Advanced database · How to add random data to the data that is not in all user data-How to add avatar data for Dragonfly Q system users without avatars-Yacao Technology kir
This content is mainly used for learning. The avatar is just an example field, which can be applied to other aspects.
Problem background:
The Dragonfly q Ultimate Edition automatically assigns user accounts and logs in based on mobile device information, skipping the step of user registration and uploading avatars, so a large number of users do not have avatars.
At this point, you need to add random avatars to these users and organize the following execution statements:
update users
set avatar='http://qingtingcun.youyacao.com/qiniu_202110270837150713870048.png'
where id IN(
select A.* from(select id from users where avatar='' order by rand() limit 10) AS A
);This statement is to randomly find 10 items without avatar each time and update them to the specified avatar address:
http://qingtingcun.youyacao.com/qiniu_202110270837150713870048.png
Then if we want to randomly update several different avatars then the code is
update users
set avatar='图片1'
where id IN(
select A.* from(select id from users where avatar='' order by rand() limit 10) AS A
);
update users
set avatar='图片2'
where id IN(
select A.* from(select id from users where avatar='' order by rand() limit 10) AS A
);
update users
set avatar='图片3'
where id IN(
select A.* from(select id from users where avatar='' order by rand() limit 10) AS A
);And so on, it is randomly updated to these three avatars, and so on, if you put a few more avatars and execute it a few times, it will be ok soon.
Effect
Execute it several times until it prompts that 0 lines are affected, indicating that all users have added avatars.
