查询某字段不重复记录的SQL语句该怎么写？

   建表语句如下：

   

/*
Navicat MySQL Data Transfer
Source Host     : localhost:3306
Source Database : test
Target Host     : localhost:3306
Target Database : test
Date: 2013-08-19 21:51:49
*/

SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for users
-- ----------------------------
DROP TABLE IF EXISTS `users`;
CREATE TABLE `users` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  `age` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of users
-- ----------------------------
INSERT INTO `users` VALUES ('1', 'huanhuan', '20');
INSERT INTO `users` VALUES ('2', 'xiaoxiao', '20');
INSERT INTO `users` VALUES ('3', 'dada', '20');
INSERT INTO `users` VALUES ('4', 'xiaoxiao', '20');
INSERT INTO `users` VALUES ('5', 'jiaojiao', '20');
INSERT INTO `users` VALUES ('6', 'dada', '20');
INSERT INTO `users` VALUES ('7', 'wenwen', '20');
INSERT INTO `users` VALUES ('8', 'wenwen', '20');

    将表建完之后，我们会发现，users表的name列值重复了，那么这时候，我们想name列不重复的记录该怎么写？想一想，我们可以使用group by函数对name进行分组，将name列划分成若干个组，然后对这些组进行处理，处理的时候，我们用到having和count函数，来对name进行筛选和统计，SQL如下：

   

select name,age from users group by name having count(*) = 1;