MySQL index optimization, performance analysis, and explain usage

Note:
1, like only when the data is listed as a string, and like is not the beginning of the index will be effective
2, greater than less than the index will only be effective when the data is listed as integral type
3. If you want to use or, and you want the index to take effect, you can only index each column in the OR condition separately

Reference documents:
Use of explain:
Http://database.51cto.com/art/201108/284783.htm
Http://www.jb51.net/article/50649.htm
Indexing and optimization:
Http://www.cnblogs.com/hustcat/archive/2009/10/28/1591648.html

MySQL index optimization, performance analysis, and explain usage