Question

SQL不是我的强项，我正在努力寻找这个问题的解决方案。我试图弄清楚如何根据以下逻辑得到结果集。当A不在B中时选择记录A或如果记录出现在B和A中则选择B.我尝试了以下联合，它返回了我在两个表中当天匹配的所有记录，但我无法弄清楚如何拉我需要从两个表中获得的数据。

SELECT 'a',PurchaseOrderLine.iPurchaseOrderLineId, sProductDescription 
FROM PurchaseOrderLine 
WHERE PurchaseOrderLine.dRequiredDate  = convert(date, getdate())
UNION 
SELECT 'b',PurchaseOrderLine.iPurchaseOrderLineId, sProductDescription 
FROM GoodsIn
INNER JOIN PurchaseOrderLine 
    ON PurchaseOrderLine.iPurchaseOrderLineId = GoodsIn.iPurchaseOrderLineId
WHERE GoodsIn.dDateDelivered =  getdate())

Answer 1

您可以执行左外连接，并在select中使用ISNULL或CASE语句来返回所需的值。

我将证明：

SELECT 
    CASE WHEN b.iPurchaseOrderLineId IS NOT NULL THEN 'b' ELSE 'a' END AS [Source],
    a.iPurchaseOrderLineId,
    ISNULL(b.sProductDescription, a.sProductDescription) AS [sProductDescription]
FROM PurchaseOrderLine AS a
    LEFT JOIN GoodsIn AS b ON a.iPurchaseOrderLineId = b.iPurchaseOrderLineId
                           AND b.dDateDelivered = GETDATE()
WHERE b.iPurchaseOrderLineId IS NOT NULL 
      OR a.dRequiredDate = CONVERT(DATE, GETDATE())

希望有所帮助！

Answer 2

希望这会对你有所帮助：只是一个与你相似的例子。

create table A(id int  , name char(12))
go

create table B(id int  , name char(12))
go

insert into A values (1,'ABC'),(3,'WXY')
insert into B values (1,'ABC'),(2,'AAA')


SELECT a.id,a.name FROM A EXCEPT SELECT * FROM B
UNION  
SELECT a.id,a.name FROM A inner join b on a.id=b.id and a.name=b.name

感谢!!!

Answer 3

如果我理解正确，假设GoodsIn = B，你可以尝试这种方式。

SELECT 'a',PurchaseOrderLine.iPurchaseOrderLineId, sProductDescription 
FROM PurchaseOrderLine 
LEFT JOIN GoodsIn
    ON PurchaseOrderLine.iPurchaseOrderLineId = GoodsIn.iPurchaseOrderLineId
WHERE PurchaseOrderLine.dRequiredDate  = convert(date, getdate())
AND GoodsIn.iPurchaseOrderLineId IS NULL
UNION 
SELECT 'b',PurchaseOrderLine.iPurchaseOrderLineId, sProductDescription 
FROM GoodsIn
INNER JOIN PurchaseOrderLine 
    ON PurchaseOrderLine.iPurchaseOrderLineId = GoodsIn.iPurchaseOrderLineId
WHERE GoodsIn.dDateDelivered =  getdate());

你也可以按照你所描述的那样逐字尝试（假设sProductDescription在PurchaseOrderLine中）：

＆＃34;当A不在B＆＃34;

时选择记录A.

SELECT 'a',PurchaseOrderLine.iPurchaseOrderLineId, sProductDescription 
FROM PurchaseOrderLine 
WHERE iPurchaseOrderLineId NOT IN(SELECT iPurchaseOrderLineId FROM GoodsIn)

或以这种方式：

SELECT 'a',PurchaseOrderLine.iPurchaseOrderLineId, sProductDescription 
FROM PurchaseOrderLine 
WHERE NOT EXISTS(SELECT * FROM GoodsIn 
    WHERE GoodsIn.iPurchaseOrderLineId=PurchaseOrderLine.iPurchaseOrderLineId)

或使用EXCEPT：

SELECT 'a',PurchaseOrderLine.iPurchaseOrderLineId, sProductDescription 
FROM PurchaseOrderLine 
EXCEPT 
SELECT 'a', iPurchaseOrderLineId, sProductDescription 
FROM GoodsIn;

只需提示，根据您的需求量身定制。

SQL：在A中选择A而不是B，或在A和B中选择B.

3 个答案: