Sql server 2005 求和函数的SQL查询

我有两张桌子，一张是贷款桌，一张是会员桌。现在在Loan中我有totalamount列，在Member中我有membertype列，在Loan中我有根据membertype的各种贷款。现在我想使用SUM函数根据memtype计算totalamount

我尝试了以下方法：

select sum(totalamount) from loan,member where member.mem_type='Regular'

你的意思是这样的：

select sum(totalamount) AS Total 
from loan
JOIN member ON Memberid=loan.Memberid   
where member.mem_type='Regular'

select sum(totalamount) AS Total,member.mem_type 
from loan
JOIN member ON Memberid=loan.Memberid   
where member.mem_type='Regular'
GROUP BY member.mem_type

或者，如果您还想选择

mem_type

，则如下所示：

select sum(totalamount) AS Total 
from loan
JOIN member ON Memberid=loan.Memberid   
where member.mem_type='Regular'

select sum(totalamount) AS Total,member.mem_type 
from loan
JOIN member ON Memberid=loan.Memberid   
where member.mem_type='Regular'
GROUP BY member.mem_type

你的意思是这样的：

select sum(totalamount) AS Total 
from loan
JOIN member ON Memberid=loan.Memberid   
where member.mem_type='Regular'

select sum(totalamount) AS Total,member.mem_type 
from loan
JOIN member ON Memberid=loan.Memberid   
where member.mem_type='Regular'
GROUP BY member.mem_type

或者，如果您还想选择

mem_type

，则如下所示：

select sum(totalamount) AS Total 
from loan
JOIN member ON Memberid=loan.Memberid   
where member.mem_type='Regular'

select sum(totalamount) AS Total,member.mem_type 
from loan
JOIN member ON Memberid=loan.Memberid   
where member.mem_type='Regular'
GROUP BY member.mem_type

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成员表的Memberid是Loan table中的外键请使用。成员表的Memberid是Loan table中的外键请使用。