Sql server 返回膨胀总计的多个子表的总计

如果表2中有多个匹配项，则将“TotalTons”乘以。如果我删除了join，它是可以的，但是我必须有WHERE子句的table2日期

样本：

TABLE1 - RegId (int) pk, RegDate (date), CityId, Tons1(int), Tons2(int)

TABLE2 - RegId(int) fk, OtherDate (date)

TABLE3 - id, City

    SELECT c.City
        , SUM(t1.Tons1 + t1.Tons2) as 'TotalTons'

    FROM Table1 t1
    JOIN Table2 t2 ON t1.RegId = t2.RegId
    JOIN table3 c ON t1.CityId = c.Id
    WHERE YEAR(t2.OtherDate) = '2016'
    GROUP BY c.City

结果

TABLE1
(20, '2016-2-2', 3, 2, 3)
(21, '2016-4-12', 7, 3, 5)
(22, '2016-4-12', 7, 6, 3)


TABLE 2
(20, '2016-2-2')
(20, '2016-2-3')
(20, '2016-2-5')
(20, '2016-2-1')
(21, '2016-5-12')
(22, '2016-9-2')


TABLE 3
(3, 'Dallas')
(7, 'Kansas')

达拉斯的总吨数是5，但因为表2中有5行不同的Regid20，所以乘以4倍

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如何使其停止将总和乘以t2结果？

您可以使用exists和sub查询替换联接：

City    TotalTons
----    ---------
Dallas  20 (should be 5)
Kansas  17 (Correct)

试试这个：

SELECT c.City
, SUM(t1.Tons1 + t1.Tons2) as 'TotalTons'
FROM Table1 t1
JOIN table3 c ON t1.CityId = c.Id
WHERE EXISTS (
     SELECT 1
     FROM Table2 t2
     WHERE t2.RegId = t1.RegId
     AND YEAR(t2.OtherDate) = '2016'
)
GROUP BY c.City

---

希望有帮助。：）

这很有效，谢谢。这是因为当存在匹配时，它只从子查询返回1，而不是返回匹配的行。如果任何行或ROE与条件匹配，则exists返回true。

DECLARE @TABLE1 TABLE(RegId INT,RegDate DATE, CityId INT, Tons1 INT, Tons2 INT)
INSERT INTO @TABLE1 VALUES
(20, '2016-2-2', 3, 2, 3),(21, '2016-4-12', 7, 3, 5),(22, '2016-4-12', 7, 6, 3)

DECLARE @TABLE2 TABLE(RegId INT,OtherDate DATE)
INSERT INTO @TABLE2 VALUES (20, '2016-2-2'),(20, '2016-2-3'),(20, '2016-2-5'),
(20, '2016-2-1'),(21, '2016-5-12'),(22, '2016-9-2')

DECLARE @TABLE3 TABLE(id INT,City NVARCHAR(10))
INSERT INTO @TABLE3 VALUES (3, 'Dallas'),(7, 'Kansas')

SELECT DISTINCT B.City,B.TotalTons FROM ( SELECT T2.*,CityId FROM @TABLE2 T2 
LEFT JOIN @TABLE1 T1 ON T1.RegId = T2.RegId ) A LEFT JOIN (SELECT CityId,City, SUM(Tons1+Tons2) TotalTons 
FROM @TABLE3 T3 LEFT JOIN @TABLE1 T1 ON T1.CityId = T3.id GROUP BY CityId,City ) B ON A.CityId = B.CityId
WHERE YEAR(OtherDate) = '2016' -- change your date clause