按类别和子类别统计总记录

Question

我有一个 table，其中包含国家和城市的所有员工数据

主要tableTbl_Emp

ID  Name                       Dept       CountryID        CityID
1   Arun Bikas Das              IT          1               1
2   Abhineet Prakash            IT          1               1
3   Avnish Dhoundiyal           HR          2               5
4   Amit Batra                  HR          3               6
5   Ajay Sethi                  AC          3               6
6   Amarendra Pandey            AC          3               6
7   Abhijit Singh               ADM         1               3
8   Anil Kumar                  ADM         1               4
9   Mahesh Venu                 MAR         1               7
10  Mohamed Rafi                MAR         1               9

Tbl_County 是

C_ID    Country
1       India
2       USA
3       UK

tbl_city 是

C_ID    City      CountryID
1       Delhi       1
2       Delhi       1
3       Mumbai      1
4       Nagpur      1
5       NewYork     2
6       Caneda      3
7       Jaipur      1
9       Panjab      1

我想 select 按县计算雇员人数：

 Country    Employees
 -------    ---------
 India          6 
 USA            1 
 UK             3

，城市也一样：

City      Employees
-------   ---------
Delhi           2 
Mumbai          1 
NewYork         1 
Canada          3 
Nagpur          1 
Jaipur          1 
Panjab          1

Answer 1

对城市做同样的事情。请在发帖前多做一些搜索，这是一件很常见的事情，你应该已经找到了很多例子。这样做将有助于减少发布的低质量问题的数量。

SELECT C.Country, COUNT(*) AS CountryCount
FROM Tbl_Emp E
INNER JOIN TblCounty C
    ON E.CountryID = C.C_ID
GROUP BY C.Country

Answer 2

SQL COUNT(*) :

COUNT(*)函数returns一个table中的记录数：

SELECT COUNT(*) FROM table_name;

以下查询将为您提供基于国家/地区的计数：

SELECT        COUNT(*) AS Count, Tbl_Country.Country
FROM            Tbl_Country INNER JOIN
                         Tbl_Emp ON Tbl_Country.C_ID = Tbl_Emp.CountryId
GROUP BY Tbl_Country.Country

试试城市查询，语法同上

Answer 3

对于国家/地区计数：

select 
min(c.Country),
count(e.CountryID) as Employees
from 
Tbl_Emp e
join Tbl_County c on e.CountryID = c.c_id
group by e.CountryID

城市数：

select 
min(c.city),
count(e.CityID) as Employees
from 
Tbl_Emp e
join tbl_city c on e.CityID = c.c_id
group by e.CityID

这可以是其他解决方案：

select 
    c.Country,
    e.Employees
from (
    select
        CountryID, count(CountryID) as Employees
    from Tbl_Emp
    group by CountryID
) as e  
join Tbl_County c on e.CountryID = c.c_id


select 
    c.city,
    e.Employees
from (
    select
        CityID, count(CityID) as Employees
    from Tbl_Emp
    group by CityID
) as e
join tbl_city c on e.CityID = c.c_id

按类别和子类别统计总记录

Count total records by category and subcategory

sql

sql-server

group-by

count