값이 없으면 MySQL에서 SUM 함수를 사용하여 '0'을 반환합니다.

Question

값이 존재하지 않으면 내 합계 함수가 '0'을 반환하도록합니다. 다음에 문제가있는 경우 누구든지 식별 할 수 있습니다. SQL 명령. 나는 유착의 순서를 변경하지만이

SqlCommand scGetPostings = new SqlCommand(@" 
SELECT 
    D1.dr, 
    D1.cr, 
    D1.asset_no, 
    (open_bal + dr - cr) AS closing_balance 
FROM (SELECT 
     COALESCE(SUM(dr_amount), 0) AS dr, 
     COALESCE(SUM(cr_amount), 0) AS cr, 
     asset_no 
     FROM posting, sysasset 
     WHERE posting.asset_no = @AssetNumber 
     AND period >= asset_open_per 
     GROUP BY asset_no) AS D1, asset 
WHERE D1.asset_no = asset.asset_no", DataAccess.AssetConnection); 

Answer 1

이 시도 차이를 만들어되지 않았습니다

SELECT 
    asset.asset_no, 
    COALESCE(dr, 0) AS dr, 
    COALESCE(cr, 0) AS cr, 
    (open_bal + COALESCE(dr, 0) - COALESCE(cr, 0)) AS closing_balance 
FROM 
    asset LEFT JOIN 
    (SELECT 
     SUM(dr_amount) AS dr, 
     SUM(cr_amount) AS cr, 
     asset_no 
     FROM posting, sysasset 
     WHERE posting.asset_no = @AssetNumber 
     AND period >= asset_open_per 
     GROUP BY asset_no) AS D1 
ON D1.asset_no = asset.asset_no 

Answer 2

사용 if condition을 명세서에 :

SqlCommand scGetPostings = new SqlCommand(@" 
SELECT 
    D1.dr, 
    D1.cr, 
    D1.asset_no, 
    (open_bal + dr - cr) AS closing_balance 
FROM (SELECT 
     SUM(if(dr_amount is null , 0 , dr_amount)) AS dr, 
     SUM(if(cr_amount is null , 0 , cr_amount)) AS cr, 
     asset_no 
     FROM posting, sysasset 
     WHERE posting.asset_no = @AssetNumber 
     AND period >= asset_open_per 
     GROUP BY asset_no) AS D1, asset 
WHERE D1.asset_no = asset.asset_no", DataAccess.AssetConnection);