Follow the HSP step-by-step approach to Mysql optimization _mysql

In the second episode

1.show status like ' com% ' is equivalent to show status sessions like ' com% ' centennial--Displays current console situation

Show global status like ' com% '--shows the number of databases from boot to query

Show sessions status like ' Com_select ';

Show status like ' uptime '--how long has it been started
Show status like ' connections '--Number of connections

Slow_queries the number of slow queries (default is 10)

For MyISAM databases, be cleaned regularly.
Optimize table name, otherwise its delete record is not emptied
Ordering by null disables sorting
Use join instead of subquery
In finance, you can use fixed-point numbers to place data decimal, not to use float, because float loses data. such as float (10,5),
In a date type, use numeric values instead of datastmp