SQL計算/總和多列

Question

我想使用在單個查詢中的樣本數據計數/總結多個字段和期望的結果列出如下：

MemID claimNum ItemID PaidAmt 
123 1234  4  5 
123 2309  4  5 
123 1209  4  5 
123 1209  8  2.2 
123 1210  8  2.2 

期望結果

MemID count(claimNum) count(ItemID) sum(PaidAmt) 
123 3    3    15 
123 2    2    4.4 

Answer 1

使用組通過項目ID

select MemID, count(claimNum), count(ItemID), sum(PaidAmt) 
from my_table 
group by MemID, ItemID 

Answer 2

看起來要分組雙方MemID和項目ID：

select MemID, count(claimNum), count(ItemID), sum(PaidAmt) 
    from the_table 
group by MemID, ItemID