MySQL advanced technology-transaction processing and lock, mysql Transaction Processing

MySQL advanced technology-transaction processing and lock, mysql Transaction Processing
MySQL advanced technology-transaction processing and lock
How does mysql lock a row of data with transactions and locks so that two users are not allowed to read a row of data simultaneously?

This cannot be implemented. Even if mysql locks a single row of data, other threads still have read locks. I think you can add a field to this table to implement this function, indicates whether the flag is read by a thread. When the flag is read, it can be changed to 1. When other threads select the flag, the flag is set to 0.

How can I lock a mysql table when I lock it?

Lock table and unlock statement:

Lock tables Table name write | read;
Unlock tables;