將查詢轉換為 SQL Server 語法

Question

我一直在從 Chegg 那里得到幫助，大多數給我的答案對我都不起作用。 我的第一個任務是編寫一個查詢，其中列出分配給大多數項目的員工。

一種回應是：

select emp_name 
from employee 
where dept_ID in ( select dept_ID from project group by dept_ID order by count(proj_ID) desc);

我得到的錯誤：

消息 1033，級別 15，狀態 1，第 3 行 ORDER BY 子句在視圖、內聯函數、派生表、子查詢和公共表表達式中無效，除非還指定了 TOP、OFFSET 或 FOR XML。

第二個反應是

select w1.emp_id
from work_period w1
group by w1.emp_id
having count(w1.proj_id) = (select max(count(w2.proj_id)) from work_period w2 group by w2.emp_id);

我得到的錯誤是：

消息 130，級別 15，狀態 1，第 8 行無法對包含聚合或子查詢的表達式執行聚合函數。

第三個回應是

Select emp_ID,emp_Name 
from Employee inner join Project on Employee.Dept_ID = Project.Dept_ID 
group by emp_ID,emp_Name 
having count(Proj_ID) = max(count(Proj_ID));

錯誤信息：

消息 130，級別 15，狀態 1，第 13 行無法對包含聚合或子查詢的表達式執行聚合函數。

非常感謝有關如何解決這些查詢之一的任何幫助

如果有幫助，這是創建我的數據庫的腳本

create table department
(
  dept_ID int not null ,
  dept_name char(50) NOT NULL,
  manager_ID int not null,
  manager_start_date date not null,

  constraint Dept_PK primary key (dept_ID),
  constraint D_Name_AK unique (dept_name)
);
insert into department values(1,'abc',1,'2019-01-08');
insert into department values(2,'abc2',2,'2019-01-08');
insert into department values(3,'abc3',2,'2019-01-08');
insert into department values(4,'abc4',2,'2019-01-08');

/*project table done*/
create table project
(
  proj_ID int not null,
  proj_name varchar(20) not null,
  dept_ID int not null,
  proj_location varchar(20) not null,

  constraint Proj_ID_PK primary key (proj_ID),
  constraint Proj_Dep_FK foreign key (dept_ID) references department(dept_ID)
);
insert into project values ( 1,'project1',1,'india');
insert into project values ( 2,'project2',2,'US');

/*employee table done*/
create table employee
(
  emp_ID int NOT NULL ,
  emp_name char(50) not null,
  emp_ssn char(11) not null,
  emp_address char(50) not null,
  salary decimal(10,2) not null,
  sex char(1) not null,
  date_of_birth date not null,
  dept_ID int not null,
  supervisor_ID int null,

  constraint emp_PK primary key(emp_ID),
  constraint emp_Name_AK unique (emp_name),
  constraint emp_SSN_AK unique (emp_ssn),
  constraint sup_FK foreign key(supervisor_ID) references employee(emp_ID),
  constraint empDep_FK foreign key(dept_ID) references department(dept_ID)
);

insert into employee values( 1,'jagmeet', 'ssn','patel nagar',300,'M','1997-07-01',1,1);

insert into employee values( 2,'harpreet', 'ssn1','patel nagar2',300,'F','1997-07-01',1,2);
/*Department location table done*/
create table dept_location
(
  dept_ID int not null,
  location char(50) not null,

  constraint dept_location_PK primary key(dept_ID, location),
  constraint dept_FK foreign key (dept_ID) references department(dept_ID)
);
insert into dept_location values(1,'loc1');

insert into dept_location values(2,'loc2');

/*dependent table done*/
create table dependent
(
  dependent_ID int not null ,
  emp_ID int NOT NULL,
  dependent_name varchar(20) NOT NULL,
  dependent_sex char(1) NOT NULL,
  dependent_DOB date not null,
  dep_relation varchar(10) not null,

  constraint dep_ID_PK primary key (dependent_ID),
  constraint deb_emp_ID_FK foreign key (emp_ID) references employee(emp_ID)
);
insert into dependent values (1,2,'deptname','M','2018-01-09','rel1');

insert into dependent values (2,1,'deptname2','F','2018-01-09','rel2');
/*work period table done*/

create table work_period
(
  emp_ID int NOT NULL,
  proj_ID int not null,
  pay_period date not null,
  weekly_work_hrs int not null,

  constraint pay_period_PK primary key (pay_period),
  constraint WP_empID_FK foreign key (emp_ID) references employee(emp_ID),
  constraint WP_projID_FK foreign key (proj_ID) references project(proj_ID)
);
insert into work_period values(1,1,'2012-09-01',7);

insert into work_period values(2,2,'2014-09-01',8);

Answer 1

您可以使用subquery獲取項目數最多的員工，以及max()和count()聚合函數。

select * from employee where dept_id in (
    select max(ct) from 
        (select count(1) ct, t1.dept_id from department t1
        inner join project t2 on t2.dept_id = t1.dept_id
        group by t1.dept_id) t3 )