未完,待补充


索引问题

  1. OR 影响索引

参考资料

http://thephper.com/?p=142
https://www.ibm.com/support/knowledgecenter/zh/SSPK3V_7.0.0/com.ibm.swg.im.soliddb.sql.doc/doc/using.indexes.to.improve.query.performance.html
https://segmentfault.com/q/1010000009426506
http://jaskey.github.io/blog/2016/01/19/mysql-bad-sql-with-no-index/