数据库关键字的执行顺序

执行顺序：

		1、from
		2、on
		3、join
		4、where
		5、group by
		6、having
		7、select
		8、distinct
		9、order by
		10、limit

熟悉小技巧：

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for group_contact_info
-- ----------------------------
DROP TABLE IF EXISTS `group_contact_info`;
CREATE TABLE `group_contact_info` (
  `active_id` varchar(25) NOT NULL,
  `modelName` varchar(25) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

-- ----------------------------
-- Records of group_contact_info
-- ----------------------------
INSERT INTO `group_contact_info` VALUES ('4', '会议');
INSERT INTO `group_contact_info` VALUES ('3', '住宿');
INSERT INTO `group_contact_info` VALUES ('4', '会议');
INSERT INTO `group_contact_info` VALUES ('1', '聚餐');
INSERT INTO `group_contact_info` VALUES ('3', '住宿');
INSERT INTO `group_contact_info` VALUES ('4', '会议');
INSERT INTO `group_contact_info` VALUES ('1', '聚餐');
INSERT INTO `group_contact_info` VALUES ('2', '行车');
INSERT INTO `group_contact_info` VALUES ('3', '住宿');
INSERT INTO `group_contact_info` VALUES ('4', '会议');

Sql语句

SELECT
	active_id,
	GROUP_CONCAT( modelName SEPARATOR ',' ) allName,
	count( 1 ) num 
FROM
	group_contact_info 
GROUP BY
	modelName 
HAVING
	num >0
ORDER BY num asc

Sql 执行效果