用法:直接在后台执行SQL语句
ALTER TABLE phome_ecms_bookname ADD INDEX (filename); //给filename字段添加索引
ALTER TABLE phome_ecms_bookname DROP INDEX filename; //删除filename字段索引
ALTER TABLE phome_ecms_bookname ADD INDEX (filename); //给filename字段添加索引
ALTER TABLE phome_ecms_bookname DROP INDEX filename; //删除filename字段索引