select * from collations;utf8编码默认的字符序是 utf8_general_ci
mysql的字符序遵从命名惯例。以_ci(表示大小写不敏感)，以_cs(表示大小写敏感)，以_bin(表示用编码值进行比较)。比如：use test;CREATE TABLE `tab_info` ( `id` int(11) NOT NULL AUTO_INCREMENT, `info` varchar(255) NOT NULL,PRIMARY KEY (`id`)) ENGINE=INNODB DEFAULT CHARSET=utf8;INSERT INTO tab_info SET info='Hello';INSERT INTO tab_info SET info='hello';SELECT * FROM tab_info WHERE info='hello';
alter table tab_info convert to character set utf8 collate utf8_bin;
