SQL Percentage Group By

Question

我需要提供員工演示者及其客戶端課堂出勤率的快速報告，並且我試圖找出SQL（針對SQL Server）中的正確查詢。

客戶端是單獨安排的課程，所以在表tSchedule中，每一行都有一個類名，課程的時間和日期，客戶端名稱，課堂演示者的名字以及客戶端的出席狀態（例如'present '，'缺席'，'缺席w /辯解'，'遲'等）

所以我需要一個SQL查詢，它會爲每個演示者輸出一行，在給定日期範圍內的演講者的班級，實際出席的總人數（即，「出席」或「缺席/出借」的出席狀態）以及這些「現在或原諒」客戶總數的百分比。

下面添加在一些細節上每回復：

tSchedule 

class   class_date  Employee_id  client_id  attendance_status 
Basket Weaving 2017-07-13  231    712    Present 
Basket Weaving 2017-07-13  231    121    Present 
Basket Weaving 2017-07-13  231    186    Absent 
Basket Weaving 2017-07-13  231    666    Absent 
Juggling   2017-07-13  900    111    Present 
Juggling   2017-07-13  900    222    Present 
Juggling   2017-07-13  900    333    Present 
Juggling   2017-07-13  900    712    Absent w/Excuse 



Expected Result of Query: 

Employee_id Clients Scheduled Clients Present or Excused Attendance Rate 
231   4     2       50% 
900   4     4       100% 

（附錄） 好吧，我已經結束了使用（如下圖）作品的查詢，但它的醜陋，我敢肯定不理想。如果有人知道獲得相同結果的最優雅的方式，我非常感謝。 （@參數1和@ param2的是爲所需的時間跨度的開始和結束日期用戶輸入的日期）

Select 
    pl.emp_id 
    ,e.last_name + ', ' + e.first_name as facilitator 
    ,count(pl.emp_id) as total_Count 
    ,(select count(*) from planner where emp_id = pl.emp_id 
     and visit_status in ('ARRIVED', 'PRESENT WITH JS', 'PRESENT NO JS') 
     and plan_date >= @param1 
     and plan_date <= @param2) as attended_Count 
    ,cast(cast((select count(*) from planner where emp_id = pl.emp_id 
     and visit_status in ('ARRIVED', 'PRESENT WITH JS','PRESENT NO JS') 
     and plan_date >= @param1 
     and plan_date <= @param2) as float)/cast((select count(*) from 
     planner where emp_id = pl.emp_id 
     and plan_date >= @param1 
     and plan_date <= @param2) as float) * 100 as decimal (18,2)) as attendance_percent 
from planner pl inner join employees e on pl.emp_id = e.emp_id 
where pl.program_id = 2 
    and pl.visittype_id in (42,173) 
    and plan_date >=@param1 
    and plan_date <= @param2 
group by pl.emp_id, e.last_name + ', ' + e.first_name 

Answer 1

select 
    status, 
    cnt*100.0/total 
from 
(select c status,count(*) cnt from attendance c group by c.status), 
(select count(*)total from attendance c)