when a user uses Ctrl+F5 to force a page refresh, the css js html file is reloaded. if the css js html file is not modified, it will take a long time to reload. after looking up the data, you can determine whether the file has been updated by adding...
SELECT COUNT (*) AS num FROM test WHERE ( a = 111AND cid = 21432 OR s_status < > yes OR t_status < > yes ) AND test . delete_time IS NULL LIMIT 1 explain the statement type is displayed as ALL. How to optimize it? ...
because of my interest, I am working on a web application in my spare time. At present, I have a big performance problem. I would like to consult you here. I hope you will not hesitate to give me your advice. there are two tables, one is the exchange ...
select * from a where aa=1 and bb=2; select * from a where in (select id from a where aa=1 and bb=2); ...
A crawler was used before hanging up, and an error of 2006-MySQL server has gone away occurred when entering the library. According to Baidu, change the my.conf file max_allowed_packet=500M wait_timeout=288000 After interactive_timeout = 288000 , t...