-- 创建部门表
create table if not exists dept3(
deptno varchar(20) primary key , -- 部门号
name varchar(20) -- 部门名字
);
-- 创建员工表
create table if not exists emp3(
eid varchar(20) primary key , -- 员工编号
ename varchar(20), -- 员工名字
age int, -- 员工年龄
dept_id varchar(20) -- 员工所属部门
);
-- 给dept3表添加数据
insert into dept3 values('1001','研发部');
insert into dept3 values('1002','销售部');
insert into dept3 values('1003','财务部');
insert into dept3 values('1004','人事部');
-- 给emp3表添加数据
insert into emp3 values('1','乔峰',20, '1001');
insert into emp3 values('2','段誉',21, '1001');
insert into emp3 values('3','虚竹',23, '1001');
insert into emp3 values('4','阿紫',18, '1001');
insert into emp3 values('5','扫地僧',85, '1002');
insert into emp3 values('6','李秋水',33, '1002');
insert into emp3 values('7','鸠摩智',50, '1002');
insert into emp3 values('8','天山童姥',60, '1003');
insert into emp3 values('9','慕容博',58, '1003');
insert into emp3 values('10','丁春秋',71, '1005');

1、查询每个部门的所属员工
2、查询研发部门的所属员工
3、查询研发部和销售部的所属员工
4、查询每个部门的员工数,并升序排序
5、查询人数大于等于3的部门，并按照人数降序排序

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1、

select ename,name from dept3,emp3 where dept_id=deptno;

 

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2、

select ename,name from dept3,emp3 where dept_id=deptno and name='研发部';

 

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3、

select ename,name from dept3,emp3 where dept_id=deptno and (name='研发部' or name='销售部');

 

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4、

select name,count(*) as 总人数 from emp3,dept3 where dept_id=deptno group by dept_id order by 总人数;

 

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5、 

select name,count(*) as 总人数 from emp3,dept3 where dept_id=deptno group by dept_id  having 总人数>=3 order by 总人数 desc;