Upda set select, mysqlupda

Upda set select, mysqlupda

In oracle and other databases, you can use the update wwm2 set wwm2.town = (select wwm5.town from wwm5 where wwm5.id = wwm2.id) format to update the database. However, I recently used mysql to find that it cannot be used like this, so I checked it online and found that mysql was solved with another statement. inner join :::;

Inner join should be used, I .e.: UPDATE friends INNER JOIN users ON friends. friendid = users. useridSET friends. friendname = users. username