相同點：它們都以一張部門表（或類別表），其它表都有部門編號DepartmentID（類別編號）
案例一：一張表
select c.DepartmentID,c.DepartmentName, t.Num AS '人員數量' from T_Department as c
left join (select DepartmentID,COUNT(*) AS Num from T_User group by DepartmentID) as t on c.DepartmentID= t.DepartmentID
核心思想就是： 拆分
1將人員表按部門編號統計數量： （ select DepartmentID,COUNT(*) AS Num from T_User group by CompanyID） 得到t： 部門編號、部門人員數量；
2將 部門表與 t ，根據部門編號聯表左連接，得到 ：部門名稱、部門人員數量
案例二：多張表
統計提交的 調查人員、設備、規范、數據來源規范 表的數量
select c.CompanyID,c.CompanyName, t1.Num AS '調查人員數量',t2.Num AS '設備數量',t.Num AS '規范數量',t3.Num AS '數據來源規范數量' from T_Company as c
left join (select CompanyID,COUNT(*) AS Num from T_Standard as s where s.HasSubmitted=1 group by CompanyID) as t on c.CompanyID= t.CompanyID
left join (select CompanyID,COUNT(*) AS Num from T_Investigator as s where s.HasSubmitted=1 group by CompanyID) as t1 on c.CompanyID= t1.CompanyID
left join (select CompanyID,COUNT(*) AS Num from T_Machine as s where s.HasSubmitted=1 group by CompanyID) as t2 on c.CompanyID= t2.CompanyID
left join (select CompanyID,COUNT(*) AS Num from T_DataSource as s where s.HasSubmitted=1 group by CompanyID) as t3 on c.CompanyID= t3.CompanyID
order by c.CompanyID
最后賦值粘貼到Excel，在Excel搞個合計：
