SQL查询-我可以汇总同一国家/地区的值

Question

我进行了以下查询：

SELECT        Projects.proj_contract_value, customers.cust_name, customers.cust_country
FROM            customers INNER JOIN
                Projects ON customers.id = Projects.id
                Where Projects.proj_date >= Convert(datetime, '2013-01-01' )
                Order By cust_country

它会准确地返回我编码的内容：

216000000   OBB                     AUSTRIA
380000000   Eurotunnel              FRANCE
42000000    FAL                     ITALY
66000000    Ferrovie della Calabria ITALY
34200000    Ferrovie del Gargano    ITALY
247300000   Ferrovie del Sud Est    ITALY
85000000    Sistemi Territoriali    ITALY
10239000    Ferrovie Nord           ITALY
33100000    Spoorwegen              NETHERLANDS
184000000   RZhD                    RUSSIAN FEDERATION
119000000   Prasa                   SOUTH AFRICA
273000000   Renfe                   SPAIN
1423000000  Thurbo                  SWITZERLAND
285000000   SBB                     SWITZERLAND
1800000000  TCDD                    TURKEY

我的最终目标是去掉客户名称，并将每个国家的价值汇总到每个国家，这样我就可以得到每个国家的总价值。我正在努力把它弄出来。我该怎么做？

Answer 1

SELECT c.cust_country, 
       sum(p.proj_contract_value) as value_sum
FROM customers c
INNER JOIN Projects p ON c.id = p.id
Where p.proj_date >= Convert(datetime, '2013-01-01')
group by c.cust_country
Order By c.cust_country