在 SQL 服務器中使用 SUM Function 時如何顯示 Null 值

Question

我在 SQL 服務器中的腳本有問題，我需要顯示 NULL 值的總共 3 列

這是我的查詢：

SELECT 
    Bucket,
        (SELECT SUM (OutstandingPrincipal)  FROM example
        WHERE [status] = 'Covid')
    AS Covid,
        (SELECT SUM (OutstandingPrincipal) FROM example
        WHERE [status] LIKE '%Disbu%')
    AS Disburs_After,
        (SELECT SUM (OutstandingPrincipal) FROM example
        WHERE [status] = 'Non Covid')
    AS Non_Covid
FROM example
WHERE Bucket IS NOT NULL
GROUP BY 
    Bucket

這怎么可能？ 提前致謝

Answer 1

如果我正確理解您的數據，則不需要所有這些子查詢，您可以使用conditional aggregation ：

select bucket,
       sum(case when status = 'Covid' then OutstandingPrincipal end) as covid,
       sum(case when status like '%Disbu%' then OutstandingPrincipal end) as Disburs_After,
       sum(case when status = 'Non Covid' then OutstandingPrincipal end) as Non_Covid
from example
where bucket is not null
group by bucket