MySQL中常用语句2
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GROUP BY 分组: 把值相同放到一个组中，最终查询出的结果只会显示组中一条记录
分组配合GROUP_CONCAT()查看组中某个字段的详细信息
配合聚合函数使用
COUNT(): 统计记录总数
如果写的是COUNT(字段名称)，字段中的值为NULL，不统计进来
写COUNT(*)会统计NULL值
SUM(): 求和
MAX()：求最大值
MIN()：求最小值
AVG()：求平均值
配合WITH ROLLUP关键使用： 会在记录末尾添加一条记录，是上面所有记录的总和
HAVING子句对分组结果进行二次筛选
ORDER BY 排序
ORDER BY 字段名称 ASC|DESC
LIMIT 限制结果集显示条数
LIMIT 值， 显示结果集的前几条记录
LIMIT offset,row_count， 从offset开始，显示几条记录,offset从0开始
-- 测试查询操作 CREATE TABLE user1( id INT UNSIGNED AUTO_INCREMENT KEY, username VARCHAR(20) NOT NULL UNIQUE COMMENT ‘编号‘, age TINYINT UNSIGNED NOT NULL DEFAULT 18 COMMENT ‘年龄‘, sex ENUM(‘男‘,‘女‘,‘保密‘) NOT NULL DEFAULT ‘保密‘ COMMENT ‘性别‘, addr VARCHAR(20) NOT NULL DEFAULT ‘北京‘, married TINYINT(1) NOT NULL DEFAULT 0 COMMENT ‘0代表未结婚，1代表已婚‘, salary FLOAT(8,2) NOT NULL DEFAULT 0 COMMENT ‘薪水‘ )ENGINE=INNODB CHARSET=UTF8; INSERT user1 VALUES(1,‘李四‘,23,‘男‘,‘北京‘,1,50000); INSERT user1(username,age,sex,addr,married,salary) VALUES(‘凌凌漆‘,27,‘女‘,‘上海‘,0,25000); INSERT user1 SET username=‘周星星‘,age=31,sex=‘女‘,addr=‘北京‘,salary=40000; INSERT user1 VALUES(NULL,‘张三‘,38,‘男‘,‘上海‘,0,15000), (NULL,‘张三风‘,38,‘男‘,‘上海‘,0,15000), (NULL,‘张子怡‘,39,‘女‘,‘北京‘,1,85000), (NULL,‘汪峰‘,42,‘男‘,‘深圳‘,1,95000), (NULL,‘刘德华‘,58,‘男‘,‘广州‘,0,115000), (NULL,‘吴亦凡‘,28,‘男‘,‘北京‘,0,75000), (NULL,‘奶茶妹‘,18,‘女‘,‘北京‘,1,65000), (NULL,‘刘嘉玲‘,36,‘女‘,‘广州‘,0,15000);
mysql> select * from user1; ‘; +----+----------+-----+-----+------+---------+-----------+ | id | username | age | sex | addr | married | salary | +----+----------+-----+-----+------+---------+-----------+ | 1 | 李四 | 23 | 男 | 北京 | 1 | 50000.00 | | 2 | 周星星 | 27 | 女 | 上海 | 0 | 25000.00 | | 3 | 凌凌漆 | 31 | 女 | 北京 | 0 | 40000.00 | | 4 | 张三 | 38 | 男 | 上海 | 0 | 15000.00 | | 5 | 张三风 | 38 | 男 | 上海 | 0 | 15000.00 | | 6 | 张子怡 | 39 | 女 | 北京 | 1 | 85000.00 | | 7 | 汪峰 | 42 | 男 | 深圳 | 1 | 95000.00 | | 8 | 刘德华 | 58 | 男 | 广州 | 0 | 115000.00 | | 9 | 吴亦凡 | 28 | 男 | 北京 | 0 | 75000.00 | | 10 | 奶茶妹 | 18 | 女 | 北京 | 1 | 65000.00 | | 11 | 刘嘉玲 | 36 | 女 | 广州 | 0 | 15000.00 | +----+----------+-----+-----+------+---------+-----------+ -- 添加desc字段 VARCHAR(100) ALTER TABLE user1 ADD userDesc VARCHAR(100); mysql> UPDATE user1 SET userDesc=‘user description‘ WHERE id<=9; Query OK, 9 rows affected (0.01 sec) Rows matched: 9 Changed: 9 Warnings: 0 mysql> SELECT * FROM user1; +----+----------+-----+-----+------+---------+-----------+------------------+ | id | username | age | sex | addr | married | salary | userDesc | +----+----------+-----+-----+------+---------+-----------+------------------+ | 1 | 李四 | 23 | 男 | 北京 | 1 | 50000.00 | user description | | 2 | 周星星 | 27 | 女 | 上海 | 0 | 25000.00 | user description | | 3 | 凌凌漆 | 31 | 女 | 北京 | 0 | 40000.00 | user description | | 4 | 张三 | 38 | 男 | 上海 | 0 | 15000.00 | user description | | 5 | 张三风 | 38 | 男 | 上海 | 0 | 15000.00 | user description | | 6 | 张子怡 | 39 | 女 | 北京 | 1 | 85000.00 | user description | | 7 | 汪峰 | 42 | 男 | 深圳 | 1 | 95000.00 | user description | | 8 | 刘德华 | 58 | 男 | 广州 | 0 | 115000.00 | user description | | 9 | 吴亦凡 | 28 | 男 | 北京 | 0 | 75000.00 | user description | | 10 | 奶茶妹 | 18 | 女 | 北京 | 1 | 65000.00 | NULL | | 11 | 刘嘉玲 | 36 | 女 | 广州 | 0 | 15000.00 | NULL | +----+----------+-----+-----+------+---------+-----------+------------------+ 11 rows in set (0.00 sec) -- 查询用户userDesc 为NULL的用户 SELECT id,username,age,userDesc FROM user1 WHERE userDesc=NULL; -- 检测NULL值 SELECT id,username,age,userDesc FROM user1 WHERE userDesc<=>NULL; -- IS [NOT] NULL检测NULL值 SELECT id,username,age,userDesc FROM user1 WHERE userDesc IS NULL; -- 测试范围BETWEEN AND -- 查询年龄在18~30之间的用户 SELECT id,username,age,sex FROM user1 WHERE age BETWEEN 18 AND 30; -- 查询薪水在10000~50000之间的用户 SELECT id,username,age,salary FROM user1 WHERE salary BETWEEN 10000 AND 50000; SELECT id,username,age,salary FROM user1 WHERE salary NOT BETWEEN 10000 AND 50000; -- 测试指定集合 IN -- 查询编号为1,3,5,7,9 SELECT id,username,age FROM user1 WHERE id IN(1,3,5,7,9,29,45,78); SELECT id,username,age FROM user1 WHERE username IN(‘king‘,‘queen‘,‘lily‘,‘rose‘); -- 测试逻辑运算符 -- 查询性别为男并且年龄>=20的用户 SELECT id,username,age,sex FROM user1 WHERE sex=‘男‘ AND age>=20; -- id>=5 && age<=30 SELECT id,username,age,sex FROM user1 WHERE id>=5 AND age<=30; SELECT id,username,age,sex FROM user1 WHERE id>=5 AND age<=30 AND sex=‘男‘; -- 要求sex=‘女‘ 并且 addr=‘北京‘ SELECT id,username,age,sex,addr FROM user1 WHERE sex=‘女‘ AND addr=‘北京‘; -- 查询薪水范围在60000~10000并且性别为男 addr=‘北京‘ SELECT id,username,age,sex,salary,addr FROM user1 WHERE salary BETWEEN 60000 AND 100000 AND sex=‘男‘ AND addr=‘北京‘; -- 查询id=1 或者 用户名为queen SELECT id,username,age FROM user1 WHERE id=1 OR username=‘queen‘; -- 测试模糊查询 SELECT id,username,age FROM user1 WHERE username=‘king‘; SELECT id,username,age FROM user1 WHERE username LIKE ‘king‘; -- 要求用户名中包含三 SELECT id,username,age,sex FROM user1 WHERE username LIKE ‘%三%‘; -- 用户名中包含n SELECT id,username,age FROM user1 WHERE username LIKE ‘%in%‘; -- 要求查询出姓张的用户 SELECT id,username,age FROM user1 WHERE username LIKE ‘张%‘; -- 查询以风结尾的用户 SELECT id,username,age FROM user1 WHERE username LIKE ‘%风‘; -- 用户名长度为三位的用户 SELECT id,username,age,sex FROM user1 WHERE username LIKE ‘___‘; SELECT id,username,age,sex FROM user1 WHERE username LIKE ‘张_‘; SELECT id,username,age,sex FROM user1 WHERE username LIKE ‘张_%‘; -- 测试分组 -- 按照性别分组sex SELECT id,username,age,sex FROM user1 GROUP BY sex; -- 按照addr分组 SELECT username,age,sex,addr FROM user1 GROUP BY addr; -- 按照性别分组，查询组中的用户名有哪些 SELECT GROUP_CONCAT(username),age,sex,addr FROM user1 GROUP BY sex; SELECT GROUP_CONCAT(username),age,sex,GROUP_CONCAT(addr) FROM user1 GROUP BY sex; -- 测试COUNT() SELECT COUNT(*) FROM user1; SELECT COUNT(id) FROM user1; -- 按照sex分组，得到用户名详情，并且分别组中的总人数 SELECT sex,GROUP_CONCAT(username) AS usersDetail,COUNT(*) AS totalUsers FROM user1 GROUP BY sex; -- 按照addr分组，得到用户名的详情，总人数，得到组中年龄的总和，年龄的最大值、最小值、平均值和 SELECT addr, GROUP_CONCAT(username) AS usersDetail, COUNT(*) AS totalUsers, SUM(age) AS sum_age, MAX(age) AS max_age, MIN(age) AS min_age, AVG(age) AS avg_age FROM user1 GROUP BY addr; -- 按照sex分组，统计组中总人数、用户名详情，得到薪水总和，薪水最大值、最小值、平均值 SELECT sex, GROUP_CONCAT(username) AS usersDetail, COUNT(*) AS totalUsers, SUM(salary) AS sum_salary, MAX(salary) AS max_salary, MIN(salary) AS min_salary, AVG(salary) AS avg_salary FROM user1 GROUP BY sex; SELECT GROUP_CONCAT(username) AS usersDetail, COUNT(*) AS totalUsers FROM user1 GROUP BY sex WITH ROLLUP; -- 按照字段的位置来分组 SELECT id,sex, GROUP_CONCAT(username) AS usersDetail, COUNT(*) AS totalUsers, SUM(salary) AS sum_salary, MAX(salary) AS max_salary, MIN(salary) AS min_salary, AVG(salary) AS avg_salary FROM user1 GROUP BY 2; -- 查询age>=30的用户并且按照sex分组 SELECT sex,GROUP_CONCAT(username) AS usersDetail, COUNT(*) AS totalUsers FROM user1 WHERE age>=30 GROUP BY sex; -- 按照addr分组，统计总人数 SELECT addr, GROUP_CONCAT(username) AS usersDetail, COUNT(*) AS totalUsers FROM user1 GROUP BY addr; -- 对于分组结果进行二次筛选，条件是组中总人数>=3 SELECT addr, GROUP_CONCAT(username) AS usersDetail, COUNT(*) AS totalUsers FROM user1 GROUP BY addr HAVING COUNT(*)>=3; SELECT addr, GROUP_CONCAT(username) AS usersDetail, COUNT(*) AS totalUsers FROM user1 GROUP BY addr HAVING totalUsers>=3; -- 按照addr分组， SELECT addr, GROUP_CONCAT(username) AS usersDetail, COUNT(*) AS totalUsers, SUM(salary) AS sum_salary, MAX(salary) AS max_salary, MIN(salary) AS min_salary, AVG(salary) AS avg_salary FROM user1 GROUP BY addr; -- 要求平均薪水>=40000 SELECT addr, GROUP_CONCAT(username) AS usersDetail, COUNT(*) AS totalUsers, SUM(salary) AS sum_salary, MAX(salary) AS max_salary, MIN(salary) AS min_salary, AVG(salary) AS avg_salary FROM user1 GROUP BY addr HAVING avg_salary>=40000; -- 测试排序 -- 按照id降序排列 SELECT id,username,age FROM user1 ORDER BY id DESC; -- 按照age升序 SELECT id,username,age FROM user1 ORDER BY age ; -- 按照多个字段排序 SELECT id,username,age FROM user1 ORDER BY age ASC,id ASC; -- 测试条件+排序 SELECT id,username,age FROM user1 WHERE age>=30; SELECT id,username,age FROM user1 WHERE age>=30 ORDER BY age DESC; -- 实现随机记录 SELECT id,username,age FROM user1 ORDER BY RAND(); -- 测试LIMIT语句 -- 显示结果集的前5条记录 SELECT id,username,age,sex FROM user1 LIMIT 5; SELECT id,username,age,sex FROM user1 LIMIT 0,5; -- 显示前3条记录 SELECT id,username,age,sex FROM user1 LIMIT 0,3; SELECT id,username,age,sex FROM user1 LIMIT 3,3; -- 更新前3条记录，将age+5 UPDATE user1 SET age=age+5 LIMIT 3; -- 按照id降序排列，更新前三条记录，将age-10 UPDATE user1 SET age=age-10 ORDER BY id DESC LIMIT 3; -- 删除前三条记录 DELETE FROM user1 LIMIT 3; DELETE FROM user1 ORDER BY id DESC LIMIT 3; -- 测试完整SELECT 语句的形式 SELECT addr, GROUP_CONCAT(username) AS usersDetail, COUNT(*) AS totalUsers, SUM(age) AS sum_age, MAX(age) AS max_age, MIN(age) AS min_age, AVG(age) AS avg_age FROM user1 WHERE id>=2 GROUP BY addr; SELECT addr, GROUP_CONCAT(username) AS usersDetail, COUNT(*) AS totalUsers, SUM(age) AS sum_age, MAX(age) AS max_age, MIN(age) AS min_age, AVG(age) AS avg_age FROM user1 WHERE id>=2 GROUP BY addr HAVING totalUsers>=2; SELECT addr, GROUP_CONCAT(username) AS usersDetail, COUNT(*) AS totalUsers, SUM(age) AS sum_age, MAX(age) AS max_age, MIN(age) AS min_age, AVG(age) AS avg_age FROM user1 WHERE id>=2 GROUP BY addr HAVING totalUsers>=2 ORDER BY totalUsers ASC; SELECT addr, GROUP_CONCAT(username) AS usersDetail, COUNT(*) AS totalUsers, SUM(age) AS sum_age, MAX(age) AS max_age, MIN(age) AS min_age, AVG(age) AS avg_age FROM user1 WHERE id>=2 GROUP BY addr HAVING totalUsers>=2 ORDER BY totalUsers ASC LIMIT 0,2; mysql> SELECT id,username,age,sex FROM user1; +----+----------+-----+-----+ | id | username | age | sex | +----+----------+-----+-----+ | 1 | 李四 | 23 | 男 | | 2 | 周星星 | 27 | 女 | | 3 | 凌凌漆 | 31 | 女 | | 4 | 张三 | 38 | 男 | | 5 | 张三风 | 38 | 男 | | 6 | 张子怡 | 39 | 女 | | 7 | 汪峰 | 42 | 男 | | 8 | 刘德华 | 58 | 男 | | 9 | 吴亦凡 | 28 | 男 | | 10 | 奶茶妹 | 18 | 女 | | 11 | 刘嘉玲 | 36 | 女 | +----+----------+-----+-----+ 11 rows in set (0.00 sec) mysql> SELECT id,username,age,sex FROM user1 -> GROUP BY addr; +----+----------+-----+-----+ | id | username | age | sex | +----+----------+-----+-----+ | 2 | 周星星 | 27 | 女 | | 1 | 李四 | 23 | 男 | | 8 | 刘德华 | 58 | 男 | | 7 | 汪峰 | 42 | 男 | +----+----------+-----+-----+ 4 rows in set (0.03 sec) mysql> SELECT id,username,age,sex,addr FROM user1 -> GROUP BY addr; +----+----------+-----+-----+------+ | id | username | age | sex | addr | +----+----------+-----+-----+------+ | 2 | 周星星 | 27 | 女 | 上海 | | 1 | 李四 | 23 | 男 | 北京 | | 8 | 刘德华 | 58 | 男 | 广州 | | 7 | 汪峰 | 42 | 男 | 深圳 | +----+----------+-----+-----+------+ 4 rows in set (0.00 sec) mysql> SELECT id,age,sex,GROUP_CONCAT(addr,username) FROM user1 -> GROUP BY sex; +----+-----+-----+-------------------------------------------------------------+ | id | age | sex | GROUP_CONCAT(addr,username) | +----+-----+-----+-------------------------------------------------------------+ | 1 | 23 | 男 | 北京李四,北京吴亦凡,上海张三,上海张三风,广州刘德华,深圳汪峰 | | 10 | 18 | 女 | 北京奶茶妹,北京张子怡,北京凌凌漆,上海周星星,广州刘嘉玲 | +----+-----+-----+-------------------------------------------------------------+ 2 rows in set (0.00 sec) mysql> SELECT COUNT(*) AS user_total FROM user1; +------------+ | user_total | +------------+ | 11 | +------------+ 1 row in set (0.00 sec) mysql> SELECT COUNT(userDesc) FROM user1; +-----------------+ | COUNT(userDesc) | +-----------------+ | 9 | +-----------------+ 1 row in set (0.00 sec) mysql> SELECT GROUP_CONCAT(username) FROM user1 -> GROUP BY sex; +-------------------------------------+ | GROUP_CONCAT(username) | +-------------------------------------+ | 李四,吴亦凡,张三,张三风,刘德华,汪峰 | | 奶茶妹,张子怡,凌凌漆,周星星,刘嘉玲 | +-------------------------------------+ 2 rows in set (0.00 sec) mysql> SELECT sex,GROUP_CONCAT(username),addr FROM user1 -> GROUP BY sex; +-----+-------------------------------------+------+ | sex | GROUP_CONCAT(username) | addr | +-----+-------------------------------------+------+ | 男 | 李四,吴亦凡,张三,张三风,刘德华,汪峰 | 北京 | | 女 | 奶茶妹,张子怡,凌凌漆,周星星,刘嘉玲 | 北京 | +-----+-------------------------------------+------+ 2 rows in set (0.00 sec) mysql> SELECT sex,GROUP_CONCAT(username) AS users_detail,COUNT(*) AS total_users FROM user1 -> GROUP BY sex; +-----+-------------------------------------+-------------+ | sex | users_detail | total_users | +-----+-------------------------------------+-------------+ | 男 | 李四,吴亦凡,张三,张三风,刘德华,汪峰 | 6 | | 女 | 奶茶妹,张子怡,凌凌漆,周星星,刘嘉玲 | 5 | +-----+-------------------------------------+-------------+ 2 rows in set (0.00 sec) mysql> SELECT sddr,GROUP_CONCAT(username) AS users_detail,COUNT(*) AS total_users,MAX(age) AS max_age, MIN(age) AS min_age,SUM(age) AS sum_age,AVG(age) AS -> avg_age FROM user1 GROUP BY addr; ERROR 1054 (42S22): Unknown column ‘sddr‘ in ‘field list‘ mysql> SELECT sddr,GROUP_CONCAT(username) AS users_detail,COUNT(*) AS total_users,MAX(age) AS max_age, MIN(age) AS min_age,SUM(age) AS sum_age,AVG(age) AS -> ; ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ‘‘ at line 1 mysql> SELECT addr,GROUP_CONCAT(username) AS users_detail,COUNT(*) AS total_users,MAX(age) AS max_age, MIN(age) AS min_age,SUM(age) AS sum_age,AVG(age) AS -> avg_age FROM user1 GROUP BY addr; +------+----------------------------------+-------------+---------+---------+---------+---------+ | addr | users_detail | total_users | max_age | min_age | sum_age | avg_age | +------+----------------------------------+-------------+---------+---------+---------+---------+ | 上海 | 周星星,张三,张三风 | 3 | 38 | 27 | 103 | 34.3333 | | 北京 | 李四,奶茶妹,吴亦凡,张子怡,凌凌漆 | 5 | 39 | 18 | 139 | 27.8000 | | 广州 | 刘德华,刘嘉玲 | 2 | 58 | 36 | 94 | 47.0000 | | 深圳 | 汪峰 | 1 | 42 | 42 | 42 | 42.0000 | +------+----------------------------------+-------------+---------+---------+---------+---------+ 4 rows in set (0.01 sec) mysql> SELECT addr,GROUP_CONCAT(username) AS users_detail,COUNT(*) AS total_users,MAX(age) AS max_age, MIN(age) AS min_age,SUM(age) AS sum_age,AVG(age) AS -> avg_age FROM user1 GROUP BY sex; +------+-------------------------------------+-------------+---------+---------+---------+---------+ | addr | users_detail | total_users | max_age | min_age | sum_age | avg_age | +------+-------------------------------------+-------------+---------+---------+---------+---------+ | 北京 | 李四,吴亦凡,张三,张三风,刘德华,汪峰 | 6 | 58 | 23 | 227 | 37.8333 | | 北京 | 奶茶妹,张子怡,凌凌漆,周星星,刘嘉玲 | 5 | 39 | 18 | 151 | 30.2000 | +------+-------------------------------------+-------------+---------+---------+---------+---------+ 2 rows in set (0.00 sec) mysql> SELECT sex,GROUP_CONCAT(username) AS users_detail,COUNT(*) AS total_users,MAX(age) AS max_age, MIN(age) AS min_age,SUM(age) AS sum_age,AVG(age) AS -> avg_age FROM user1 GROUP BY sex; +-----+-------------------------------------+-------------+---------+---------+---------+---------+ | sex | users_detail | total_users | max_age | min_age | sum_age | avg_age | +-----+-------------------------------------+-------------+---------+---------+---------+---------+ | 男 | 李四,吴亦凡,张三,张三风,刘德华,汪峰 | 6 | 58 | 23 | 227 | 37.8333 | | 女 | 奶茶妹,张子怡,凌凌漆,周星星,刘嘉玲 | 5 | 39 | 18 | 151 | 30.2000 | +-----+-------------------------------------+-------------+---------+---------+---------+---------+ 2 rows in set (0.00 sec) mysql> SELECT GROUP_CONCAT(username) AS userDetail FROM user1 WHERE age>=30 GROUP BY sex; +-------------------------+ | userDetail | +-------------------------+ | 张三,张三风,汪峰,刘德华 | | 凌凌漆,张子怡,刘嘉玲 | +-------------------------+ 2 rows in set (0.01 sec) mysql> SELECT sex,GROUP_CONCAT(username) AS userDetail FROM user1 WHERE age>=30 GROUP BY sex; +-----+-------------------------+ | sex | userDetail | +-----+-------------------------+ | 男 | 张三,张三风,汪峰,刘德华 | | 女 | 凌凌漆,张子怡,刘嘉玲 | +-----+-------------------------+ 2 rows in set (0.00 sec) mysql> SELECT sex,GROUP_CONCAT(username) AS userDetail,COUNT(*) AS totalUsers FROM user1 WHERE age>=30 GROUP BY sex; +-----+-------------------------+------------+ | sex | userDetail | totalUsers | +-----+-------------------------+------------+ | 男 | 张三,张三风,汪峰,刘德华 | 4 | | 女 | 凌凌漆,张子怡,刘嘉玲 | 3 | +-----+-------------------------+------------+ 2 rows in set (0.00 sec) mysql> SELECT adde,GROUP_CONCAT(username) AS userDetail, COUNT(*) AS total_users, SUM(salary) AS sum_salary, MAX(salary) AS max_of_salary, -> SELECT adde,GROUP_CONCAT(username) AS userDetail, COUNT(*) AS total_users, SUM(salary) AS sum_salary, MAX(salary) AS max_of_salary,; ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ‘SELECT adde,GROUP_CONCAT(username) AS userDetail, COUNT(*) AS total_users, SUM(s‘ at line 2 mysql> SELECT addr,GROUP_CONCAT(username) AS userDetail, COUNT(*) AS total_users, SUM(salary) AS sum_salary, MAX(salary) AS max_of_salary, -> MIN(salary) AS min_of_salary, AVG(salary) AS avg_of_salary FROM user1 GROUP BY addr; +------+----------------------------------+-------------+------------+---------------+---------------+---------------+ | addr | userDetail | total_users | sum_salary | max_of_salary | min_of_salary | avg_of_salary | +------+----------------------------------+-------------+------------+---------------+---------------+---------------+ | 上海 | 周星星,张三,张三风 | 3 | 55000.00 | 25000.00 | 15000.00 | 18333.333333 | | 北京 | 李四,奶茶妹,吴亦凡,张子怡,凌凌漆 | 5 | 315000.00 | 85000.00 | 40000.00 | 63000.000000 | | 广州 | 刘德华,刘嘉玲 | 2 | 130000.00 | 115000.00 | 15000.00 | 65000.000000 | | 深圳 | 汪峰 | 1 | 95000.00 | 95000.00 | 95000.00 | 95000.000000 | +------+----------------------------------+-------------+------------+---------------+---------------+---------------+ 4 rows in set (0.01 sec) mysql> SELECT addr,GROUP_CONCAT(username) AS userDetail, COUNT(*) AS total_users, SUM(salary) AS sum_salary, MAX(salary) AS max_of_salary, -> MIN(salary) AS min_of_salary, AVG(salary) AS avg_of_salary FROM user1 GROUP BY addr ORDER BY salary; +------+----------------------------------+-------------+------------+---------------+---------------+---------------+ | addr | userDetail | total_users | sum_salary | max_of_salary | min_of_salary | avg_of_salary | +------+----------------------------------+-------------+------------+---------------+---------------+---------------+ | 上海 | 周星星,张三,张三风 | 3 | 55000.00 | 25000.00 | 15000.00 | 18333.333333 | | 北京 | 李四,奶茶妹,吴亦凡,张子怡,凌凌漆 | 5 | 315000.00 | 85000.00 | 40000.00 | 63000.000000 | | 深圳 | 汪峰 | 1 | 95000.00 | 95000.00 | 95000.00 | 95000.000000 | | 广州 | 刘德华,刘嘉玲 | 2 | 130000.00 | 115000.00 | 15000.00 | 65000.000000 | +------+----------------------------------+-------------+------------+---------------+---------------+---------------+ 4 rows in set (0.01 sec) mysql> SELECT addr,GROUP_CONCAT(username) AS userDetail, COUNT(*) AS total_users, SUM(salary) AS sum_salary, MAX(salary) AS max_of_salary, -> MIN(salary) AS min_of_salary, AVG(salary) AS avg_of_salary FROM user1 GROUP BY addr ORDER BY sum_salary; +------+----------------------------------+-------------+------------+---------------+---------------+---------------+ | addr | userDetail | total_users | sum_salary | max_of_salary | min_of_salary | avg_of_salary | +------+----------------------------------+-------------+------------+---------------+---------------+---------------+ | 上海 | 周星星,张三,张三风 | 3 | 55000.00 | 25000.00 | 15000.00 | 18333.333333 | | 深圳 | 汪峰 | 1 | 95000.00 | 95000.00 | 95000.00 | 95000.000000 | | 广州 | 刘德华,刘嘉玲 | 2 | 130000.00 | 115000.00 | 15000.00 | 65000.000000 | | 北京 | 李四,奶茶妹,吴亦凡,张子怡,凌凌漆 | 5 | 315000.00 | 85000.00 | 40000.00 | 63000.000000 | +------+----------------------------------+-------------+------------+---------------+---------------+---------------+ 4 rows in set (0.01 sec) mysql> SELECT addr,GROUP_CONCAT(username) AS userDetail, COUNT(*) AS total_users, SUM(salary) AS sum_salary, MAX(salary) AS max_of_salary, -> MIN(salary) AS min_of_salary, AVG(salary) AS avg_of_salary FROM user1 GROUP BY addr HAVING avg_of_salary>=40000; +------+----------------------------------+-------------+------------+---------------+---------------+---------------+ | addr | userDetail | total_users | sum_salary | max_of_salary | min_of_salary | avg_of_salary | +------+----------------------------------+-------------+------------+---------------+---------------+---------------+ | 北京 | 李四,奶茶妹,吴亦凡,张子怡,凌凌漆 | 5 | 315000.00 | 85000.00 | 40000.00 | 63000.000000 | | 广州 | 刘德华,刘嘉玲 | 2 | 130000.00 | 115000.00 | 15000.00 | 65000.000000 | | 深圳 | 汪峰 | 1 | 95000.00 | 95000.00 | 95000.00 | 95000.000000 | +------+----------------------------------+-------------+------------+---------------+---------------+---------------+ 3 rows in set (0.00 sec) mysql> sekect * from user1 -> limit 5; ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ‘sekect * from user1 limit 5‘ at line 1 mysql> select * from user1 limit 5; +----+----------+-----+-----+------+---------+----------+------------------+ | id | username | age | sex | addr | married | salary | userDesc | +----+----------+-----+-----+------+---------+----------+------------------+ | 1 | 李四 | 23 | 男 | 北京 | 1 | 50000.00 | user description | | 2 | 周星星 | 27 | 女 | 上海 | 0 | 25000.00 | user description | | 3 | 凌凌漆 | 31 | 女 | 北京 | 0 | 40000.00 | user description | | 4 | 张三 | 38 | 男 | 上海 | 0 | 15000.00 | user description | | 5 | 张三风 | 38 | 男 | 上海 | 0 | 15000.00 | user description | +----+----------+-----+-----+------+---------+----------+------------------+ 5 rows in set (0.00 sec) mysql> SELECT * FROM user1 LIMIT 0, 3; +----+----------+-----+-----+------+---------+----------+------------------+ | id | username | age | sex | addr | married | salary | userDesc | +----+----------+-----+-----+------+---------+----------+------------------+ | 1 | 李四 | 23 | 男 | 北京 | 1 | 50000.00 | user description | | 2 | 周星星 | 27 | 女 | 上海 | 0 | 25000.00 | user description | | 3 | 凌凌漆 | 31 | 女 | 北京 | 0 | 40000.00 | user description | +----+----------+-----+-----+------+---------+----------+------------------+ 3 rows in set (0.00 sec) mysql> SELECT * FROM user1 LIMIT 3, 3; +----+----------+-----+-----+------+---------+----------+------------------+ | id | username | age | sex | addr | married | salary | userDesc | +----+----------+-----+-----+------+---------+----------+------------------+ | 4 | 张三 | 38 | 男 | 上海 | 0 | 15000.00 | user description | | 5 | 张三风 | 38 | 男 | 上海 | 0 | 15000.00 | user description | | 6 | 张子怡 | 39 | 女 | 北京 | 1 | 85000.00 | user description | +----+----------+-----+-----+------+---------+----------+------------------+ 3 rows in set (0.00 sec) mysql> UPDATE user1 SET age=age+5 WHERE id<=3; Query OK, 3 rows affected (0.01 sec) Rows matched: 3 Changed: 3 Warnings: 0 mysql> SELECT * FROM user1 LIMIT 0, 3; +----+----------+-----+-----+------+---------+----------+------------------+ | id | username | age | sex | addr | married | salary | userDesc | +----+----------+-----+-----+------+---------+----------+------------------+ | 1 | 李四 | 28 | 男 | 北京 | 1 | 50000.00 | user description | | 2 | 周星星 | 32 | 女 | 上海 | 0 | 25000.00 | user description | | 3 | 凌凌漆 | 36 | 女 | 北京 | 0 | 40000.00 | user description | +----+----------+-----+-----+------+---------+----------+------------------+ 3 rows in set (0.00 sec) mysql> SELECT * FROM user1 ORDER BY id DESC UPDATE user1 SET age=age+10 WHERE id<=3; ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ‘UPDATE user1 SET age=age+10 WHERE id<=3‘ at line 1 mysql> SELECT * FROM user1 ORDER BY id DESC; +----+----------+-----+-----+------+---------+-----------+------------------+ | id | username | age | sex | addr | married | salary | userDesc | +----+----------+-----+-----+------+---------+-----------+------------------+ | 11 | 刘嘉玲 | 36 | 女 | 广州 | 0 | 15000.00 | NULL | | 10 | 奶茶妹 | 18 | 女 | 北京 | 1 | 65000.00 | NULL | | 9 | 吴亦凡 | 28 | 男 | 北京 | 0 | 75000.00 | user description | | 8 | 刘德华 | 58 | 男 | 广州 | 0 | 115000.00 | user description | | 7 | 汪峰 | 42 | 男 | 深圳 | 1 | 95000.00 | user description | | 6 | 张子怡 | 39 | 女 | 北京 | 1 | 85000.00 | user description | | 5 | 张三风 | 38 | 男 | 上海 | 0 | 15000.00 | user description | | 4 | 张三 | 38 | 男 | 上海 | 0 | 15000.00 | user description | | 3 | 凌凌漆 | 36 | 女 | 北京 | 0 | 40000.00 | user description | | 2 | 周星星 | 32 | 女 | 上海 | 0 | 25000.00 | user description | | 1 | 李四 | 28 | 男 | 北京 | 1 | 50000.00 | user description | +----+----------+-----+-----+------+---------+-----------+------------------+ 11 rows in set (0.00 sec) mysql> UPDATE user1 SET age=age-10 ORDER BY id DESC LIMIT 0, 3; ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ‘ 3‘ at line 1 mysql> UPDATE user1 SET age=age-10 ORDER BY id DESC LIMIT 3; Query OK, 3 rows affected (0.04 sec) Rows matched: 3 Changed: 3 Warnings: 0 mysql> SELECT * FROM user1; +----+----------+-----+-----+------+---------+-----------+------------------+ | id | username | age | sex | addr | married | salary | userDesc | +----+----------+-----+-----+------+---------+-----------+------------------+ | 1 | 李四 | 28 | 男 | 北京 | 1 | 50000.00 | user description | | 2 | 周星星 | 32 | 女 | 上海 | 0 | 25000.00 | user description | | 3 | 凌凌漆 | 36 | 女 | 北京 | 0 | 40000.00 | user description | | 4 | 张三 | 38 | 男 | 上海 | 0 | 15000.00 | user description | | 5 | 张三风 | 38 | 男 | 上海 | 0 | 15000.00 | user description | | 6 | 张子怡 | 39 | 女 | 北京 | 1 | 85000.00 | user description | | 7 | 汪峰 | 42 | 男 | 深圳 | 1 | 95000.00 | user description | | 8 | 刘德华 | 58 | 男 | 广州 | 0 | 115000.00 | user description | | 9 | 吴亦凡 | 18 | 男 | 北京 | 0 | 75000.00 | user description | | 10 | 奶茶妹 | 8 | 女 | 北京 | 1 | 65000.00 | NULL | | 11 | 刘嘉玲 | 26 | 女 | 广州 | 0 | 15000.00 | NULL | +----+----------+-----+-----+------+---------+-----------+------------------+ 11 rows in set (0.00 sec) mysql> DELETE FROM user1 LIMIT 3; Query OK, 3 rows affected (0.00 sec) mysql> SELECT * FROM user1; +----+----------+-----+-----+------+---------+-----------+------------------+ | id | username | age | sex | addr | married | salary | userDesc | +----+----------+-----+-----+------+---------+-----------+------------------+ | 4 | 张三 | 38 | 男 | 上海 | 0 | 15000.00 | user description | | 5 | 张三风 | 38 | 男 | 上海 | 0 | 15000.00 | user description | | 6 | 张子怡 | 39 | 女 | 北京 | 1 | 85000.00 | user description | | 7 | 汪峰 | 42 | 男 | 深圳 | 1 | 95000.00 | user description | | 8 | 刘德华 | 58 | 男 | 广州 | 0 | 115000.00 | user description | | 9 | 吴亦凡 | 18 | 男 | 北京 | 0 | 75000.00 | user description | | 10 | 奶茶妹 | 8 | 女 | 北京 | 1 | 65000.00 | NULL | | 11 | 刘嘉玲 | 26 | 女 | 广州 | 0 | 15000.00 | NULL | +----+----------+-----+-----+------+---------+-----------+------------------+ 8 rows in set (0.00 sec)
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