Как получить статус текущего сотрудника, статус смирения, недавно присоединившийся статус в определенный период?

Question

У меня есть главная таблица сотрудников в этой таблице, есть empcode, empname, joindate, resigndate, но не упоминает ни одной даты ввода в master. не Как получить нынешних сотрудников, не работающих не уйдет в отставку, не сотрудников присоединились, в частности, даты периодов

напр:

current employees -200 
resigned employees -25 
joined employees -10 
current status  -200+10=210-25=185 

это каждый я хотел в табличном формате

Answer 1

Если у нас есть календарь размер таблицы или даты, запрос, просмотр ... и т. д., это становится намного проще.

/* example Calendar, just Months */ 
create table dbo.Calendar(
    MonthStart date primary key 
    , MonthEnd date 
); 

declare @FromDate date = '20000101'; 
declare @ThruDate date = '20301201'; 

with n as (select n from (values(0),(1),(2),(3),(4),(5),(6),(7),(8),(9)) t(n)) 
, d as (
    select DateValue=convert(date,dateadd(month 
     , row_number() over (order by (select 1)) -1, @fromdate)) 
    from   n as deka 
     cross join n as hecto 
     cross join n as kilo 
) 
insert into dbo.Calendar 
    select top (datediff(month, @FromDate, @ThruDate)+1) 
     MonthStart = dateadd(month, datediff(month, 0, DateValue), 0) 
    , MonthEnd  = dateadd(day,-1, dateadd(month, datediff(month, 0, DateValue)+1, 0)) 
    from d 
    order by DateValue; 

---

запроса с использованием common table expression, а затем sum(case when.. 1 else 0 end)

;with cte as (
select 
    c.MonthStart 
    , c.MonthEnd 
    , e.EmpCode 
    , e.JoinDate 
    , e.ResignDate 
from dbo.Calendar as c 
    inner join dbo.EmpMaster as e 
    on c.MonthEnd >= e.JoinDate 
    and c.MonthStart <= e.ResignDate 
) 
select 
    MonthStart 
    , MonthEnd 
    , CurrentEmployees = sum(
      case when JoinDate < MonthStart 
       then 1 else 0 end) 
    , Joined   = sum(
      case when JoinDate >= MonthStart and JoinDate <= MonthEnd 
       then 1 else 0 end) 
    , Resigned   = sum(
      case when ResignDate >= MonthStart and ResignDate <= MonthEnd 
       then 1 else 0 end) 
    , CurrentStatus = sum(
      case when ResignDate > MonthEnd 
       then 1 else 0 end) 
from cte 
group by 
    cte.MonthStart 
    , cte.MonthEnd 
order by cte.MonthStart; 

без КТР, и используя вместо count(case when ... then column else null end):

select 
    MonthStart 
    , MonthEnd 
    , CurrentEmployees = count (
     case when JoinDate < MonthStart 
      then EmpCode else null end) 
    , Joined   = count (
     case when JoinDate >= MonthStart and JoinDate <= MonthEnd 
      then EmpCode else null end) 
    , Resigned   = count (
     case when ResignDate >= MonthStart and ResignDate <= MonthEnd 
      then EmpCode else null end) 
    , CurrentStatus = count (
     case when ResignDate > MonthEnd 
      then EmpCode else null end) 
from (
    select 
    c.MonthStart 
    , c.MonthEnd 
    , e.EmpCode 
    , e.JoinDate 
    , e.ResignDate 
from dbo.Calendar as c 
    inner join dbo.EmpMaster as e 
    on c.MonthEnd >= e.JoinDate 
    and c.MonthStart <= e.ResignDate 
    ) as cte 
group by cte.MonthStart, cte.MonthEnd 
order by cte.MonthStart 

Каждый возвращает те же результаты: http://rextester.com/AEZTL76069

+------------+------------+------------------+--------+----------+---------------+ 
| MonthStart | MonthEnd | CurrentEmployees | Joined | Resigned | CurrentStatus | 
+------------+------------+------------------+--------+----------+---------------+ 
| 2010-01-01 | 2010-01-31 |    0 |  3 |  0 |    3 | 
| 2010-02-01 | 2010-02-28 |    3 |  1 |  0 |    4 | 
| 2010-03-01 | 2010-03-31 |    4 |  2 |  0 |    6 | 
| 2010-04-01 | 2010-04-30 |    6 |  1 |  0 |    7 | 
| 2010-05-01 | 2010-05-31 |    7 |  2 |  0 |    9 | 
| 2010-06-01 | 2010-06-30 |    9 |  1 |  0 |   10 | 
| 2010-07-01 | 2010-07-31 |    10 |  1 |  0 |   11 | 
| 2010-08-01 | 2010-08-31 |    11 |  2 |  0 |   13 | 
| 2010-09-01 | 2010-09-30 |    13 |  6 |  0 |   19 | 
| 2010-10-01 | 2010-10-31 |    19 |  2 |  0 |   21 | 
| 2010-11-01 | 2010-11-30 |    21 |  1 |  0 |   22 | 
| 2010-12-01 | 2010-12-31 |    22 |  0 |  0 |   22 | 
+------------+------------+------------------+--------+----------+---------------+