MySQL database-index of query optimization

Definition: A data structure that is specifically designed to help users quickly query data in a database. Similar to a directory in a dictionary, you can find the contents of the dictionary based on the directory to locate the data, and then get directly.

Categories: General index, uniqueness Index, full-text index, single-column index, multicolumn Index, spatial index, primary key index, combined index.

Create:

#对表增加普通索引或UNIQUE索引, the () content represents optional.
CREATE (UNIQUE)INDEX on table_name (COL01,COL02);

#用来创建普通索引, unique index, or primary key index ALTER TABLE ADD INDEX index_name (col01,col02); ALTER TABLE ADD UNIQUE (COL01,COL02); ALTER TABLE ADD PRIMARY KEY (COL01,COL02);

Reference: MySQL Index Detailed: http://blog.csdn.net/liaodehong/article/details/52190223

　　

MySQL database-index of query optimization