数据库 - 数据 - 单表查询
单表查询:
http://www.cnblogs.com/linhaifeng/articles/7267592.html
1.单表查询的语法
2.关键字的执行优先级(重点)
3.简单查询
4.where 约束
5.分组查询:group by
6.having 过滤
7.查询排序:order by
8.限制查询得记录数:limit
9.使用正则表达式查询
一、单表查询的语法:
SELECT 字段1,字段2... FROM 表名
WHERE 条件
GROUP BY field
HAVING 筛选
ORDER BY field
LIMIT 限制条数
二、关键字的执行优先级:
from
where
group by
having
select
distinct
order by
limit
说明:
1.找到表:from
2.拿着where指定的约束条件,去文件/表中取出一条条记录
3.将取出的一条条记录进行分组group by,如果没有group by,则整体作为一组
4.将分组的结果进行having过滤
5.执行select
6.去重
7.将结果按条件排序:order by
8.限制结果的显示条数
详细见:http://www.cnblogs.com/linhaifeng/articles/7372774.html
三、简单查询:
1.准备表的记录
company.employee
员工id id int
姓名 emp_name varchar
性别 sex enum
年龄 age int
入职日期 hire_date date
岗位 post varchar
职位描述 post_comment varchar
薪水 salary double
办公室 office int
部门编号 depart_id int
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 # 创建表 2 create table employee( 3 id int not null unique auto_increment, 4 name varchar(20) not null, 5 sex enum('male','female') not null default 'male', 6 age int(3) unsigned not null default 28, 7 hire_date date not null, 8 post varchar(50), 9 post_comment varchar(100), 10 salary double(15,2), 11 office int, # 一个部门一个屋子 12 depart_id int 13 ); 14 mysql> desc employee; 15 +--------------+-----------------------+------+-----+---------+----------------+ 16 | Field | Type | Null | Key | Default | Extra | 17 +--------------+-----------------------+------+-----+---------+----------------+ 18 | id | int(11) | NO | PRI | NULL | auto_increment | 19 | name | varchar(20) | NO | | NULL | | 20 | sex | enum('male','female') | NO | | male | | 21 | age | int(3) unsigned | NO | | 28 | | 22 | hire_date | date | NO | | NULL | | 23 | post | varchar(50) | YES | | NULL | | 24 | post_comment | varchar(100) | YES | | NULL | | 25 | salary | double(15,2) | YES | | NULL | | 26 | office | int(11) | YES | | NULL | | 27 | depart_id | int(11) | YES | | NULL | | 28 +--------------+-----------------------+------+-----+---------+----------------+ 29 10 rows in set (0.00 sec) 30 # 插入记录 31 #三个部门:教学,销售,运营 32 insert into employee(name,sex,age,hire_date,post,salary,office,depart_id) values 33 ('egon','male',18,'20170301','老男孩驻沙河办事处外交大使',7300.33,401,1), #以下是教学部 34 ('alex','male',78,'20150302','teacher',1000000.31,401,1), 35 ('wupeiqi','male',81,'20130305','teacher',8300,401,1), 36 ('yuanhao','male',73,'20140701','teacher',3500,401,1), 37 ('liwenzhou','male',28,'20121101','teacher',2100,401,1), 38 ('jingliyang','female',18,'20110211','teacher',9000,401,1), 39 ('jinxin','male',18,'19000301','teacher',30000,401,1), 40 ('成龙','male',48,'20101111','teacher',10000,401,1), 41 42 ('歪歪','female',48,'20150311','sale',3000.13,402,2),#以下是销售部门 43 ('丫丫','female',38,'20101101','sale',2000.35,402,2), 44 ('丁丁','female',18,'20110312','sale',1000.37,402,2), 45 ('星星','female',18,'20160513','sale',3000.29,402,2), 46 ('格格','female',28,'20170127','sale',4000.33,402,2), 47 48 ('张野','male',28,'20160311','operation',10000.13,403,3), #以下是运营部门 49 ('程咬金','male',18,'19970312','operation',20000,403,3), 50 ('程咬银','female',18,'20130311','operation',19000,403,3), 51 ('程咬铜','male',18,'20150411','operation',18000,403,3), 52 ('程咬铁','female',18,'20140512','operation',17000,403,3) 53 ; 54 mysql> select * from employee; 55 +----+------------+--------+-----+------------+-----------------------------------------+--------------+------------+--------+-----------+ 56 | id | name | sex | age | hire_date | post | post_comment | salary | office | depart_id | 57 +----+------------+--------+-----+------------+-----------------------------------------+--------------+------------+--------+-----------+ 58 | 1 | egon | male | 18 | 2017-03-01 | 老男孩驻沙河办事处外交大使 | NULL | 7300.33 | 401 | 1 | 59 | 2 | alex | male | 78 | 2015-03-02 | teacher | NULL | 1000000.31 | 401 | 1 | 60 | 3 | wupeiqi | male | 81 | 2013-03-05 | teacher | NULL | 8300.00 | 401 | 1 | 61 | 4 | yuanhao | male | 73 | 2014-07-01 | teacher | NULL | 3500.00 | 401 | 1 | 62 | 5 | liwenzhou | male | 28 | 2012-11-01 | teacher | NULL | 2100.00 | 401 | 1 | 63 | 6 | jingliyang | female | 18 | 2011-02-11 | teacher | NULL | 9000.00 | 401 | 1 | 64 | 7 | jinxin | male | 18 | 1900-03-01 | teacher | NULL | 30000.00 | 401 | 1 | 65 | 8 | 成龙 | male | 48 | 2010-11-11 | teacher | NULL | 10000.00 | 401 | 1 | 66 | 9 | 歪歪 | female | 48 | 2015-03-11 | sale | NULL | 3000.13 | 402 | 2 | 67 | 10 | 丫丫 | female | 38 | 2010-11-01 | sale | NULL | 2000.35 | 402 | 2 | 68 | 11 | 丁丁 | female | 18 | 2011-03-12 | sale | NULL | 1000.37 | 402 | 2 | 69 | 12 | 星星 | female | 18 | 2016-05-13 | sale | NULL | 3000.29 | 402 | 2 | 70 | 13 | 格格 | female | 28 | 2017-01-27 | sale | NULL | 4000.33 | 402 | 2 | 71 | 14 | 张野 | male | 28 | 2016-03-11 | operation | NULL | 10000.13 | 403 | 3 | 72 | 15 | 程咬金 | male | 18 | 1997-03-12 | operation | NULL | 20000.00 | 403 | 3 | 73 | 16 | 程咬银 | female | 18 | 2013-03-11 | operation | NULL | 19000.00 | 403 | 3 | 74 | 17 | 程咬铜 | male | 18 | 2015-04-11 | operation | NULL | 18000.00 | 403 | 3 | 75 | 18 | 程咬铁 | female | 18 | 2014-05-12 | operation | NULL | 17000.00 | 403 | 3 | 76 +----+------------+--------+-----+------------+-----------------------------------------+--------------+------------+--------+-----------+ 77 18 rows in set (0.00 sec) 78 #ps:如果在windows系统中,插入中文字符,select的结果为空白,可以将所有字符编码统一设置成gbk
2.查询
1.简单查询
SELECT id,name,sex,age,hire_date,post,post_comment,salary,office,depart_id
FROM employee;
SELECT * FROM employee;
SELECT name,salary FROM employee;
2.避免重复DISTINCT
SELECT DISTINCT post FROM employee;
3.通过四则运算查询
SELECT name, salary*12 FROM employee;
SELECT name, salary*12 AS Annual_salary FROM employee;
SELECT name, salary*12 Annual_salary FROM employee;
4.定义显示格式
CONCAT() 函数用于连接字符串
SELECT CONCAT('姓名: ',name,' 年薪: ', salary*12) AS Annual_salary
FROM employee;
CONCAT_WS() 第一个参数为分隔符
SELECT CONCAT_WS(':',name,salary*12) AS Annual_salary
FROM employee;
3.练习:
1. <名字:egon> | <薪资:87603.96>
select concat('<名字:',name,'>'),concat('<薪资:',salary*12,'>') from employee;
2. 查出所有的岗位(去掉重复)
select distinct post from employee;
3. 查出所有员工名字,以及他们的年薪,年薪的字段名为annual_year
select name,salary*12 annual_salary from employee;
四、where约束:
1. 比较运算符:> < >= <= <> !=
2. between 80 and 100 值在80到100之间 100 >= x >= 80
3. in(80,90,100) 值是80或90或100 in (80 or 90 or 100)
4. like 'egon%'
pattern可以是%或_,
%表示任意多字符
_表示一个字符
5. 逻辑运算符:在多个条件直接可以使用逻辑运算符 and or not
语法:
#1:单条件查询
SELECT name FROM employee
WHERE post='sale';
#2:多条件查询
SELECT name,salary FROM employee
WHERE post='teacher' AND salary>10000;
#3:关键字BETWEEN AND
SELECT name,salary FROM employee
WHERE salary BETWEEN 10000 AND 20000;
SELECT name,salary FROM employee
WHERE salary NOT BETWEEN 10000 AND 20000;
#4:关键字IS NULL(判断某个字段是否为NULL不能用等号,需要用IS)
SELECT name,post_comment FROM employee
WHERE post_comment IS NULL;
SELECT name,post_comment FROM employee
WHERE post_comment IS NOT NULL;
SELECT name,post_comment FROM employee
WHERE post_comment=''; 注意''是空字符串,不是null
ps:
执行
update employee set post_comment='' where id=2;
再用上条查看,就会有结果了
#5:关键字IN集合查询
SELECT name,salary FROM employee
WHERE salary=3000 OR salary=3500 OR salary=4000 OR salary=9000 ;
SELECT name,salary FROM employee
WHERE salary IN (3000,3500,4000,9000) ;
SELECT name,salary FROM employee
WHERE salary NOT IN (3000,3500,4000,9000) ;
#6:关键字LIKE模糊查询
通配符’%’
SELECT * FROM employee
WHERE name LIKE 'eg%';
通配符’_’
SELECT * FROM employee
WHERE name LIKE 'al__';
练习:
1. 查看岗位是teacher的员工姓名、年龄
2. 查看岗位是teacher且年龄大于30岁的员工姓名、年龄
3. 查看岗位是teacher且薪资在9000-1000范围内的员工姓名、年龄、薪资
4. 查看岗位描述不为NULL的员工信息
5. 查看岗位是teacher且薪资是10000或9000或30000的员工姓名、年龄、薪资
6. 查看岗位是teacher且薪资不是10000或9000或30000的员工姓名、年龄、薪资
7. 查看岗位是teacher且名字是jin开头的员工姓名、年薪
select name,age from employee where post = 'teacher';
select name,age from employee where post='teacher' and age > 30;
select name,age,salary from employee where post='teacher' and salary between 9000 and 10000;
select * from employee where post_comment is not null;
select name,age,salary from employee where post='teacher' and salary in (10000,9000,30000);
select name,age,salary from employee where post='teacher' and salary not in (10000,9000,30000);
select name,salary*12 from employee where post='teacher' and name like 'jin%';
五、分组查询 group by:
1.什么是分组,为什么要分组?
#1、首先明确一点:分组发生在where之后,即分组是基于where之后得到的记录而进行的
#2、分组指的是:将所有记录按照某个相同字段进行归类,比如针对员工信息表的职位分组,或者按照性别进行分组等
#3、为何要分组呢?
取每个部门的最高工资
取每个部门的员工数
取男人数和女人数
小窍门:‘每’这个字后面的字段,就是我们分组的依据
#4、大前提:
可以按照任意字段分组,但是分组完毕后,比如group by post,只能查看post字段,如果想查看组内信息,需要借助于聚合函数
2.ONLY_FULL_GROUP_BY
#查看MySQL 5.7默认的sql_mode如下:
mysql> select @@global.sql_mode;
ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
#!!!注意
ONLY_FULL_GROUP_BY的语义就是确定select target list中的所有列的值都是明确语义,简单的说来,在ONLY_FULL_GROUP_BY模式下,target list中的值要么是来自于聚集函数的结果,要么是来自于group by list中的表达式的值。
#设置sql_mole如下操作(我们可以去掉ONLY_FULL_GROUP_BY模式):
mysql> set global sql_mode='STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';
!!!SQL_MODE设置!!!
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 mysql> select @@global.sql_mode; 2 +-------------------+ 3 | @@global.sql_mode | 4 +-------------------+ 5 | | 6 +-------------------+ 7 row in set (0.00 sec) 8 9 mysql> select * from emp group by post; 10 +----+------+--------+-----+------------+----------------------------+--------------+------------+--------+-----------+ 11 | id | name | sex | age | hire_date | post | post_comment | salary | office | depart_id | 12 +----+------+--------+-----+------------+----------------------------+--------------+------------+--------+-----------+ 13 | 14 | 张野 | male | 28 | 2016-03-11 | operation | NULL | 10000.13 | 403 | 3 | 14 | 9 | 歪歪 | female | 48 | 2015-03-11 | sale | NULL | 3000.13 | 402 | 2 | 15 | 2 | alex | male | 78 | 2015-03-02 | teacher | NULL | 1000000.31 | 401 | 1 | 16 | 1 | egon | male | 18 | 2017-03-01 | 老男孩驻沙河办事处外交大使 | NULL | 7300.33 | 401 | 1 | 17 +----+------+--------+-----+------------+----------------------------+--------------+------------+--------+-----------+ 18 rows in set (0.00 sec) 19 20 21 #由于没有设置ONLY_FULL_GROUP_BY,于是也可以有结果,默认都是组内的第一条记录,但其实这是没有意义的 22 23 mysql> set global sql_mode='ONLY_FULL_GROUP_BY'; 24 Query OK, 0 rows affected (0.00 sec) 25 26 mysql> quit #设置成功后,一定要退出,然后重新登录方可生效 27 Bye 28 29 mysql> use db1; 30 Database changed 31 mysql> select * from emp group by post; #报错 32 ERROR 1055 (42000): 'db1.emp.id' isn't in GROUP BY 33 mysql> select post,count(id) from emp group by post; #只能查看分组依据和使用聚合函数 34 +----------------------------+-----------+ 35 | post | count(id) | 36 +----------------------------+-----------+ 37 | operation | 5 | 38 | sale | 5 | 39 | teacher | 7 | 40 | 老男孩驻沙河办事处外交大使 | 1 | 41 +----------------------------+-----------+ 42 rows in set (0.00 sec)
3.group by
单独使用GROUP BY关键字分组
SELECT post FROM employee GROUP BY post;
注意:我们按照post字段分组,那么select查询的字段只能是post,想要获取组内的其他相关信息,需要借助函数
GROUP BY关键字和GROUP_CONCAT()函数一起使用
SELECT post,GROUP_CONCAT(name) FROM employee GROUP BY post;#按照岗位分组,并查看组内成员名
SELECT post,GROUP_CONCAT(name) as emp_members FROM employee GROUP BY post;
GROUP BY与聚合函数一起使用
select post,count(id) as count from employee group by post;#按照岗位分组,并查看每个组有多少人
强调:
如果我们用unique的字段作为分组的依据,则每一条记录自成一组,这种分组没有意义
多条记录之间的某个字段值相同,该字段通常用来作为分组的依据
4.聚合函数
#强调:聚合函数聚合的是组的内容,若是没有分组,则默认一组
示例:
SELECT COUNT(*) FROM employee;
SELECT COUNT(*) FROM employee WHERE depart_id=1;
SELECT MAX(salary) FROM employee;
SELECT MIN(salary) FROM employee;
SELECT AVG(salary) FROM employee;
SELECT SUM(salary) FROM employee;
SELECT SUM(salary) FROM employee WHERE depart_id=3;
5.练习:
1. 查询岗位名以及岗位包含的所有员工名字
2. 查询岗位名以及各岗位内包含的员工个数
3. 查询公司内男员工和女员工的个数
4. 查询岗位名以及各岗位的平均薪资
5. 查询岗位名以及各岗位的最高薪资
6. 查询岗位名以及各岗位的最低薪资
7. 查询男员工与男员工的平均薪资,女员工与女员工的平均薪资
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 #题目1: 2 mysql> select post,group_concat(name) from employee group by post; 3 +-----------------------------------------+---------------------------------------------------------+ 4 | post | group_concat(name) | 5 +-----------------------------------------+---------------------------------------------------------+ 6 | operation | 张野,程咬金,程咬银,程咬铜,程咬铁 | 7 | sale | 歪歪,丫丫,丁丁,星星,格格 | 8 | teacher | alex,wupeiqi,yuanhao,liwenzhou,jingliyang,jinxin,成龙 | 9 | 老男孩驻沙河办事处外交大使 | egon | 10 +-----------------------------------------+---------------------------------------------------------+ 11 #题目2: 12 mysql> select post,count(id) from employee group by post; 13 +-----------------------------------------+-----------+ 14 | post | count(id) | 15 +-----------------------------------------+-----------+ 16 | operation | 5 | 17 | sale | 5 | 18 | teacher | 7 | 19 | 老男孩驻沙河办事处外交大使 | 1 | 20 +-----------------------------------------+-----------+ 21 #题目3: 22 mysql> select sex,count(id) from employee group by sex; 23 +--------+-----------+ 24 | sex | count(id) | 25 +--------+-----------+ 26 | male | 10 | 27 | female | 8 | 28 +--------+-----------+ 29 #题目4: 30 mysql> select post,avg(salary) from employee group by post; 31 +-----------------------------------------+---------------+ 32 | post | avg(salary) | 33 +-----------------------------------------+---------------+ 34 | operation | 16800.026000 | 35 | sale | 2600.294000 | 36 | teacher | 151842.901429 | 37 | 老男孩驻沙河办事处外交大使 | 7300.330000 | 38 +-----------------------------------------+---------------+ 39 #题目5 40 mysql> select post,max(salary) from employee group by post; 41 +-----------------------------------------+-------------+ 42 | post | max(salary) | 43 +-----------------------------------------+-------------+ 44 | operation | 20000.00 | 45 | sale | 4000.33 | 46 | teacher | 1000000.31 | 47 | 老男孩驻沙河办事处外交大使 | 7300.33 | 48 +-----------------------------------------+-------------+ 49 #题目6 50 mysql> select post,min(salary) from employee group by post; 51 +-----------------------------------------+-------------+ 52 | post | min(salary) | 53 +-----------------------------------------+-------------+ 54 | operation | 10000.13 | 55 | sale | 1000.37 | 56 | teacher | 2100.00 | 57 | 老男孩驻沙河办事处外交大使 | 7300.33 | 58 +-----------------------------------------+-------------+ 59 #题目7 60 mysql> select sex,avg(salary) from employee group by sex; 61 +--------+---------------+ 62 | sex | avg(salary) | 63 +--------+---------------+ 64 | male | 110920.077000 | 65 | female | 7250.183750 | 66 +--------+---------------+
六、having 过滤:
having 与 where 不一样的地方在于:
#!!!执行优先级从高到低:where > group by > having
#1. Where 发生在分组group by之前,因而Where中可以有任意字段,但是绝对不能使用聚合函数。
#2. Having发生在分组group by之后,因而Having中可以使用分组的字段,无法直接取到其他字段,可以使用聚合函数
验证:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 mysql> select @@sql_mode; 2 +--------------------+ 3 | @@sql_mode | 4 +--------------------+ 5 | ONLY_FULL_GROUP_BY | 6 +--------------------+ 7 row in set (0.00 sec) 8 9 mysql> select * from emp where salary > 100000; 10 +----+------+------+-----+------------+---------+--------------+------------+--------+-----------+ 11 | id | name | sex | age | hire_date | post | post_comment | salary | office | depart_id | 12 +----+------+------+-----+------------+---------+--------------+------------+--------+-----------+ 13 | 2 | alex | male | 78 | 2015-03-02 | teacher | NULL | 1000000.31 | 401 | 1 | 14 +----+------+------+-----+------------+---------+--------------+------------+--------+-----------+ 15 row in set (0.00 sec) 16 17 mysql> select * from emp having salary > 100000; 18 ERROR 1463 (42000): Non-grouping field 'salary' is used in HAVING clause 19 20 mysql> select post,group_concat(name) from emp group by post having salary > 10000;#错误,分组后无法直接取到salary字段 21 ERROR 1054 (42S22): Unknown column 'salary' in 'having clause' 22 mysql> select post,group_concat(name) from emp group by post having avg(salary) > 10000; 23 +-----------+-------------------------------------------------------+ 24 | post | group_concat(name) | 25 +-----------+-------------------------------------------------------+ 26 | operation | 程咬铁,程咬铜,程咬银,程咬金,张野 | 27 | teacher | 成龙,jinxin,jingliyang,liwenzhou,yuanhao,wupeiqi,alex | 28 +-----------+-------------------------------------------------------+ 29 rows in set (0.00 sec)
练习:
1. 查询各岗位内包含的员工个数小于2的岗位名、岗位内包含员工名字、个数
2. 查询各岗位平均薪资大于10000的岗位名、平均工资
3. 查询各岗位平均薪资大于10000且小于20000的岗位名、平均工资
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 #题1: 2 mysql> select post,group_concat(name),count(id) from employee group by post having count(id) < 2; 3 +-----------------------------------------+--------------------+-----------+ 4 | post | group_concat(name) | count(id) | 5 +-----------------------------------------+--------------------+-----------+ 6 | 老男孩驻沙河办事处外交大使 | egon | 1 | 7 +-----------------------------------------+--------------------+-----------+ 8 #题目2: 9 mysql> select post,avg(salary) from employee group by post having avg(salary) > 10000; 10 +-----------+---------------+ 11 | post | avg(salary) | 12 +-----------+---------------+ 13 | operation | 16800.026000 | 14 | teacher | 151842.901429 | 15 +-----------+---------------+ 16 #题目3: 17 mysql> select post,avg(salary) from employee group by post having avg(salary) > 10000 and avg(salary) <20000; 18 +-----------+--------------+ 19 | post | avg(salary) | 20 +-----------+--------------+ 21 | operation | 16800.026000 | 22 +-----------+--------------+
七、查询排序 order by:
按单列排序
SELECT * FROM employee ORDER BY salary;
SELECT * FROM employee ORDER BY salary ASC;
SELECT * FROM employee ORDER BY salary DESC;
按多列排序:先按照age排序,如果年纪相同,则按照薪资排序
SELECT * from employee
ORDER BY age,
salary DESC;
练习:
1. 查询所有员工信息,先按照age升序排序,如果age相同则按照hire_date降序排序
2. 查询各岗位平均薪资大于10000的岗位名、平均工资,结果按平均薪资升序排列
3. 查询各岗位平均薪资大于10000的岗位名、平均工资,结果按平均薪资降序排列
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 #题目1 2 mysql> select * from employee ORDER BY age asc,hire_date desc; 3 #题目2 4 mysql> select post,avg(salary) from employee group by post having avg(salary) > 10000 order by avg(salary) asc; 5 +-----------+---------------+ 6 | post | avg(salary) | 7 +-----------+---------------+ 8 | operation | 16800.026000 | 9 | teacher | 151842.901429 | 10 +-----------+---------------+ 11 #题目3 12 mysql> select post,avg(salary) from employee group by post having avg(salary) > 10000 order by avg(salary) desc; 13 +-----------+---------------+ 14 | post | avg(salary) | 15 +-----------+---------------+ 16 | teacher | 151842.901429 | 17 | operation | 16800.026000 | 18 +-----------+---------------+
八、限制查询得记录数 limit:
示例:
SELECT * FROM employee ORDER BY salary DESC
LIMIT 3; #默认初始位置为0
SELECT * FROM employee ORDER BY salary DESC
LIMIT 0,5; #从第0开始,即先查询出第一条,然后包含这一条在内往后查5条
SELECT * FROM employee ORDER BY salary DESC
LIMIT 5,5; #从第5开始,即先查询出第6条,然后包含这一条在内往后查5条
练习:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 # 分页显示,每页5条 2 mysql> select * from employee limit 0,5; 3 +----+-----------+------+-----+------------+-----------------------------------------+--------------+------------+--------+-----------+ 4 | id | name | sex | age | hire_date | post | post_comment | salary | office | depart_id | 5 +----+-----------+------+-----+------------+-----------------------------------------+--------------+------------+--------+-----------+ 6 | 1 | egon | male | 18 | 2017-03-01 | 老男孩驻沙河办事处外交大使 | NULL | 7300.33 | 401 | 1 | 7 | 2 | alex | male | 78 | 2015-03-02 | teacher | | 1000000.31 | 401 | 1 | 8 | 3 | wupeiqi | male | 81 | 2013-03-05 | teacher | NULL | 8300.00 | 401 | 1 | 9 | 4 | yuanhao | male | 73 | 2014-07-01 | teacher | NULL | 3500.00 | 401 | 1 | 10 | 5 | liwenzhou | male | 28 | 2012-11-01 | teacher | NULL | 2100.00 | 401 | 1 | 11 +----+-----------+------+-----+------------+-----------------------------------------+--------------+------------+--------+-----------+ 12 rows in set (0.00 sec) 13 14 mysql> select * from employee limit 5,5; 15 +----+------------+--------+-----+------------+---------+--------------+----------+--------+-----------+ 16 | id | name | sex | age | hire_date | post | post_comment | salary | office | depart_id | 17 +----+------------+--------+-----+------------+---------+--------------+----------+--------+-----------+ 18 | 6 | jingliyang | female | 18 | 2011-02-11 | teacher | NULL | 9000.00 | 401 | 1 | 19 | 7 | jinxin | male | 18 | 1900-03-01 | teacher | NULL | 30000.00 | 401 | 1 | 20 | 8 | 成龙 | male | 48 | 2010-11-11 | teacher | NULL | 10000.00 | 401 | 1 | 21 | 9 | 歪歪 | female | 48 | 2015-03-11 | sale | NULL | 3000.13 | 402 | 2 | 22 | 10 | 丫丫 | female | 38 | 2010-11-01 | sale | NULL | 2000.35 | 402 | 2 | 23 +----+------------+--------+-----+------------+---------+--------------+----------+--------+-----------+ 24 rows in set (0.00 sec) 25 26 mysql> select * from employee limit 10,5; 27 +----+-----------+--------+-----+------------+-----------+--------------+----------+--------+-----------+ 28 | id | name | sex | age | hire_date | post | post_comment | salary | office | depart_id | 29 +----+-----------+--------+-----+------------+-----------+--------------+----------+--------+-----------+ 30 | 11 | 丁丁 | female | 18 | 2011-03-12 | sale | NULL | 1000.37 | 402 | 2 | 31 | 12 | 星星 | female | 18 | 2016-05-13 | sale | NULL | 3000.29 | 402 | 2 | 32 | 13 | 格格 | female | 28 | 2017-01-27 | sale | NULL | 4000.33 | 402 | 2 | 33 | 14 | 张野 | male | 28 | 2016-03-11 | operation | NULL | 10000.13 | 403 | 3 | 34 | 15 | 程咬金 | male | 18 | 1997-03-12 | operation | NULL | 20000.00 | 403 | 3 | 35 +----+-----------+--------+-----+------------+-----------+--------------+----------+--------+-----------+ 36 rows in set (0.00 sec)
九、使用正则表达式查询:
SELECT * FROM employee WHERE name REGEXP '^ale';
SELECT * FROM employee WHERE name REGEXP 'on$';
SELECT * FROM employee WHERE name REGEXP 'm{2}';
小结:对字符串匹配的方式
WHERE name = 'egon';
WHERE name LIKE 'yua%';
WHERE name REGEXP 'on$';
练习:
查看所有员工中名字是jin开头,n或者g结尾的员工信息
select * from employee where name regexp '^jin.*[n|g]$';