mysql-randomly-select

1. http://www.mysqltutorial.org/select-random-records-database-table.aspx

2. https://stackoverflow.com/questions/4329396/mysql-select-10-random-rows-from-600k-rows-fast

3. http://mysql.rjweb.org/doc.php/random

4. http://jan.kneschke.de/projects/mysql/order-by-rand/