(1). 写出sql语句,查询所有年龄大于20岁的员工(2分)
(2). 写出sql语句,查询所有年龄小于25岁的女性员工(3分)
(3). 写出sql语句,统计男女员工各有多少名(3分)
(4). 写出sql语句,按照年龄倒序获取员工信息(3分)
(5). 写出sql语句,获取员工中哪个姓名具有重名现象(3分)
(6). 写出sql语句,查询所有姓张的员工(3分)
(7). 写出sql语句,查询住址为北京的前3条记录(3分)
(8). 写出sql语句,查询员工总数(3分)
(9). 写出sql语句,向表中插入一条记录(2分)
(10).写出sql语句,修改员工张四的住址为南京(2分)
(11).写出sql语句,删除年龄大于24岁的女员工(2分)
cmd/Java连接数据库是在这个步骤之后才能连接成功的,所以我们到这步之后才算是进入了MYSQL数据库
基本操作:
cd :change directory的缩写。数据库里面有很多表
show databases;
show tables;
desc employee;
drop database hzyc98;
drop table employee;
create table employee (Name char(30) not null,Sex char(8),Age int, Address char(30));
【约束条件】
创建表:约束(默认值、非空、独一无二)
PRI:主键primary(一个表只有一个主键,主键是赋给表头的某个列(Field)的)
primary key
not null
unique
default
添加列表
insert into employee (Name,Sex,Age , Address ) value('张三', '女',19,'北京' );
insert into employee (Name,Sex,Age , Address ) value('李四', '男',20,'上海' );
insert into employee (Name,Sex,Age , Address ) value('王五', '女',25,'广州' );
insert into employee (Name,Sex,Age , Address ) value('王五', '男',22,'北京' );
insert into employee (Name,Sex,Age , Address ) value('薛六', '女',20,'北京' );
insert into employee (Name,Sex,Age , Address ) value('赵七', '男',28,'上海' );
insert into employee (Name,Sex,Age , Address ) value('张四', '女',23,'北京' );
答案仅供参考:
注意这里有个update不能加from,易错
(1). 写出sql语句,查询所有年龄大于20岁的员工(2分)
Select * from employee where age >20;
(2). 写出sql语句,查询所有年龄小于25岁的女性员工(3分)
Select * from employee where age <25 and sex = ‘女’;
(3). 写出sql语句,统计男女员工各有多少名(3分)
Select sex,count(*) from employee group by sex;
(4). 写出sql语句,按照年龄倒序获取员工信息(3分)
Select * from employee order by age desc;
(5). 写出sql语句,获取员工中哪个姓名具有重名现象(3分)
Select name from employee group by name count(name)>1;
(6). 写出sql语句,查询所有姓张的员工(3分)
//模糊查询like
Select * from employee where name like ‘张%’;
(7). 写出sql语句,查询住址为北京的前3条记录(3分)
select * from employee where address = '北京'order by address asc limit 0,3;
(8). 写出sql语句,查询员工总数(3分)
Select count(name) from employee;
(9). 写出sql语句,向表中插入一条记录(2分)
Insert into employee (Name ,Sex , Age , Address) value ('张四', '女',23,'北京');
(10).写出sql语句,修改员工张四的住址为南京(2分)
Update employee set address = ‘南京’ where name = ‘张四’;
(11).写出sql语句,删除年龄大于24岁的女员工(2分)
Delete from employee where age > 24 and sex = ‘女’;