mysql数据库如何创建索引

Table / for city
-- ----------------------------
DROP TABLE IF EXISTS city;
CREATE TABLE city (
id int(11) NOT NULL AUTO_INCREMENT,
country varchar(255) DEFAULT NULL,
name varchar(255) DEFAULT NULL,
state varchar(255) DEFAULT NULL,
code_name varchar(255) DEFAULT NULL,
PRIMARY KEY (id),
KEY index_id (id) USING BTREE,
KEY index_name (name),
KEY index_mass (country,name),
FULLTEXT KEY country (country)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;

普通索引
ALTER TABLE city ADD INDEX index_name (name);
主键索引
ALTER TABLE city ADD PRIMARY KEY (id);
全文索引
ALTER TABLE city ADD FULLTEXT (country);
多列索引
ALTER TABLE city ADD INDEX index_mass (country,name);