MySQL Command Shortcuts, Help Commands, and Administration Tips

This article presents a collection of handy MySQL client shortcuts, such as \? for help, \c to cancel the current command, \r to reconnect, \d to change the command delimiter, \e to write to a file and execute multiple statements, \G for vertical output, \q to quit, and many others including source, status, system, use, prompt, nopager, pager, charset, warnings, and nowarning.

The built‑in help command can be used in several ways, for example mysql> help, mysql> help contents, mysql> help select, mysql> help create, mysql> help create user, mysql> help status, and mysql> help show.

Common mysqladmin operations are demonstrated:

Change password: mysqladmin -uroot -p123 password 123456 Shutdown the server (useful for multi‑instance setups): mysqladmin -uroot -p123 -S /tmp/mysql.sock shutdown Create a database: mysqladmin -uroot -p create hahashen Drop a database (with confirmation warning): mysqladmin -uroot -p drop hahashen Show server variables (e.g., server_id): mysqladmin -uroot -p variables | grep server_id Check if the server is alive: mysqladmin -uroot -p123 ping Reload privilege tables (equivalent to FLUSH PRIVILEGES): mysqladmin -uroot -p123 reload Flush binary logs (useful before setting up replication): mysqladmin -uroot -p123 flush-log When encountering high CPU usage (e.g., sustained 85% load), the article outlines a step‑by‑step troubleshooting process:

Identify the MySQL process ID: ps -ef | grep -i mysql Monitor CPU consumption of that process in real time: top -p 124468 -H (replace 124468 with the actual PID).

Find the corresponding MySQL thread ID:

select thread_id, name, PROCESSLIST_ID, THREAD_OS_ID from threads where THREAD_OS_ID = 124468;

Retrieve the SQL text executed by that thread:

select sql_text from performance_schema.events_statements_current where thread_id = 124468 \G;

These commands help pinpoint the exact statement causing the CPU spike, enabling targeted optimization or termination.