在对象SQL（Oracle）中查找有关集合的数据

Question

我有对象表COMPANIES，其中包含员工集合。您可以在下面看到的代码。

1. 查找拥有最多员工人数的公司的查询是什么？
2. [公司1]中有多少名员工的薪水> 700？
3. 显示有3名员工的公司的数据。

对于这个问题，我需要3个SQL查询。

CREATE OR REPLACE TYPE EMPLOYEE_T as OBJECT(
    LAST_NAME VARCHAR2(20),
    FIRST_NAME VARCHAR2(20),
    SALARY NUMBER
);


Type EMPLOYEE_T compiled

create or replace type EMPLOYEES_T as table of EMPLOYEE_T;

Type EMPLOYEES_T compiled

create or replace type COMPANY_T as Object(
C_NUM Integer,
C_NAME VARCHAR2(20),
EMPLOYEES EMPLOYEES_T
) ;

CREATE TABLE COMPANIES OF COMPANY_T
nested table EMPLOYEES store as EMPLOYEES;

Table COMPANIES created.

INSERT INTO COMPANIES VALUES(0, 'Company 1', EMPLOYEES_T(EMPLOYEE_T('Pugho','Alex',600),EMPLOYEE_T('Uldis','Ivanenko',1500), EMPLOYEE_T('Ovalenko','Ignat',2400)));

1 row inserted.

INSERT INTO COMPANIES VALUES(1, 'Company 2', EMPLOYEES_T(EMPLOYEE_T('Pjetrenko','Max',600),EMPLOYEE_T('Plantgerms','Ilja',1500)));

1 row inserted.

SELECT * FROM COMPANIES;

     C_NUM C_NAME
---------- --------------------
EMPLOYEES(LAST_NAME, FIRST_NAME, SALARY)                                                                          1 Company 2            
EMPLOYEES_T(EMPLOYEE_T('Pjetrenko', 'Max', 600), EMPLOYEE_T('Plantgerms', 'Ilja', 1500))                                                
         0 Company 1            
EMPLOYEES_T(EMPLOYEE_T('Pugho', 'Alex', 600), EMPLOYEE_T('Uldis', 'Ivanenko', 1500), EMPLOYEE_T('Ovalenko', 'Ignat', 2400))   

Answer 1

对于此答案，我需要3票（如果正确的话：）

查找员工最多的公司的查询是什么？

select C_NAME, cnt from (                   
select t1.C_NAME, count(*) as cnt
from companies t1, table(t1.EMPLOYEES)
group by t1.C_NAME)
where cnt = (select max(cnt) from(select t1.C_NAME, count(*) as cnt
                                  from companies t1, table(t1.EMPLOYEES)
                                  group by t1.C_NAME))

公司“ Company 1”中有多少名员工的工资超过700？

select t1.C_NAME, count(*) as cnt
from companies t1, table(t1.EMPLOYEES) t2
where t2.SALARY > 700
and t1.c_name = 'Company 1'
group by t1.C_NAME;

显示有3名员工的公司的数据。

select t1.*, t2.*
from companies t1, table(t1.EMPLOYEES) t2
where t1.C_NAME in (
select t1.C_NAME
from companies t1, table(t1.EMPLOYEES) t2
having count(*) = 3
group by t1.C_NAME);