Sql 如果不存在，则插入两个表的总和

我有一种情况，我想求两个表之间的差的和。问题是第二个表中可能存在一行，然后我想将其作为新行插入

伪

SELECT T1.seller, T1.code, T1.amount - T2.amount

请看图片以了解解释

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您需要进行一次完整的外部联接，然后进行汇总。如果您只运行内部查询，您将得到每个可能的行组合（在t1中是独占的，在t1和t2中都存在，在t2中是独占的）-然后将其分组并进行求和

SELECT  Seller ,
        Code ,
        SUM(Tab1_amt - Tab2_amt) AS Amount
FROM    ( SELECT    COALESCE(tab1.Seller, tab2.Seller) AS Seller ,
                    COALESCE(tab1.code, tab2.code) AS Code ,
                    COALESCE(tab1.amount, 0) AS tab1_amt ,
                    COALESCE(tab2.amount, 0) AS tab2_amt
          FROM      tab1
                    FULL OUTER JOIN tab2 ON tab1.seller = tab2.seller
                                            AND tab1.code = tab2.code
        ) AS Tbl
GROUP BY Seller ,
        Code

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请参见

我认为您需要一个

完全联接

（除非您确实希望将行插入到第一个表中）

如果确实需要将行插入表1，则需要执行2个操作，首先插入，然后选择：

INSERT Table1 (Seller, Code, Amount)
SELECT  t2.Seller, t2.Code, 0 AS Amount
FROM    Table2 t2
WHERE   NOT EXISTS
        (   SELECT  1
            FROM    Table1 t1
            WHERE   t1.Seller = t2.Seller
            AND     COALESCE(t1.Code, 0) = COALESCE(t2.Code, 0)
        );

SELECT  t1.Seller, 
        t1.Code, 
        t1.Amount - COALESCE(t2.Amount, 0) AS Amount
FROM    Table1 t1
        LEFT JOIN Table2 t2
            ON t1.Seller = t2.Seller
            AND COALESCE(t1.Code, 0) = COALESCE(t2.Code, 0);

编辑

如果每个表中的行不是unqiue，需要求和，则需要在子查询中求和，因为连接将引入交叉连接：

以这些数据为例

Table1
Seller  Code    Amount
VL      500     10
VL      500     20

Table2
Seller  Code    Amount
VL      500     30
VL      500     5

当您加入此网站时，您将获得：

t1.Seller   t1.Code t1.Amount   t2.Seller   t2.Code t2.Amount
VL          500     10          VL          500     30
VL          500     10          VL          500     5
VL          500     20          VL          500     30
VL          500     20          VL          500     5

然后，差值之和为-10，而不是-5

SELECT  COALESCE(t1.Seller, t2.Seller) AS Seller,
        COALESCE(t1.Code, t2.Code) AS Code,
        COALESCE(t1.Amount, 0) - COALESCE(t2.Amount, 0) AS Amount
FROM    (   SELECT  Seller, Code, SUM(Amount) AS Amount
            FROM    Table1 
            GROUP BY Seller, Code
        ) t1
        FULL JOIN 
        (   SELECT  Seller, Code, SUM(Amount) AS Amount
            FROM    Table2 
            GROUP BY Seller, Code
        ) t2
            ON t1.Seller = t2.Seller
            AND COALESCE(t1.Code, 0) = COALESCE(t2.Code, 0);

编辑2

中的

UNION

方法将比完全联接执行得更好：

SELECT  Seller, Code, Amount = SUM(Amount)
FROM    (   SELECT  Seller, Code, Amount
            FROM    Table1
            UNION
            SELECT  Seller, Code, -Amount
            FROM    Table2
        ) t
GROUP BY Seller, Code

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像这样的？您没有告诉要插入到“因此tableX”中的表

在表X中插入（卖方、代码、金额）值（T1.seller、T1.code、T1.amount-T2.amount）
从表2中选择计数（*）小于1的计数（*）

请注意，在insert to apply filter之后，将筛选器作为select语句放置

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您没有指定所需的sql类型，因此我无法说明这是否有效

您使用的是什么DBMS？您尝试过什么？

选择T1.seller，T1.code，（T1.amount-T2.amount）作为T1.ID=T2.ID上的T1内部连接T2的TAmountSum

Im使用SQL2008选择T1.seller，T1.shortcutcode，（T1.amount-T2.amount）作为T1.seller=T2.seller上的表1内部连接表2 T2的总金额，但这会得到重复的行

选择distinct T1.seller，T1.shortcutcode，（T1.amount-T2.amount）作为T1.seller=T2.seller上的表1 T1内部联接表2 T2中的总金额

表列是什么？

 DECLARE @T1 TABLE(
    seller VARCHAR(10),
    code VARCHAR(3) NULL,
    amount MONEY
)

 DECLARE @T2 TABLE(
    seller VARCHAR(10),
    code VARCHAR(3) NULL,
    amount MONEY
)

INSERT INTO @T1 VALUES
('VL',NULL,1),
('VL','317',70005.6)

INSERT INTO @T2 VALUES
('VL',NULL,0.5),
('VL','500',4450)

SELECT seller,code,SUM(amount) [amount] FROM 
(
SELECT * FROM @T1
UNION ALL
SELECT seller,code,-amount as amount FROM @T2
) T
GROUP BY seller,code

insert into tableX (seller,code,amount) values (T1.seller, T1.code, T1.amount -T2.amount)
select count(*) from table2 having count(*) < 1

 DECLARE @T1 TABLE(
    seller VARCHAR(10),
    code VARCHAR(3) NULL,
    amount MONEY
)

 DECLARE @T2 TABLE(
    seller VARCHAR(10),
    code VARCHAR(3) NULL,
    amount MONEY
)

INSERT INTO @T1 VALUES
('VL',NULL,1),
('VL','317',70005.6)

INSERT INTO @T2 VALUES
('VL',NULL,0.5),
('VL','500',4450)

SELECT seller,code,SUM(amount) [amount] FROM 
(
SELECT * FROM @T1
UNION ALL
SELECT seller,code,-amount as amount FROM @T2
) T
GROUP BY seller,code