基于2列从UNION结果中过滤重复项

Question

我得到了两个select查询的联合，其中一个被查询的表是一个临时表，以确保输出记录(因此临时表具有每个日期的预期输出，但Sale列的缺省值为0

输出结果示例如下所示：

ProductID  | Product Desc | TransactionDate | Sale
1011021    | SD DOG       | 2017-01-07      | 0
1011021    | SD DOG       | 2017-01-07      | $17
1011021    | SD DOG       | 2017-01-14      | 0
1011021    | SD DOG       | 2017-01-14      | $15
1011021    | SD DOG       | 2017-01-21      | $21
1011021    | SD DOG       | 2017-01-28      | 0
1011021    | SD DOG       | 2017-01-28      | $21

Union按行去重，如何让Union根据productID和transactionDate列去重，去掉Sale为0的重复？

--查询如下

SELECT transactionProducts.productID, products.productDesc, sum(salePrice) as Sale, transactionDate 
FROM products LEFT JOIN transactionProducts on products.productID = transactionProducts.productID 
LEFT JOIN transactions ON transactionProducts.transactionID = transactions.transactionID 
LEFT JOIN productCategory on productCategory.productID = products.productID 
LEFT JOIN categories on categories.categoryID = productCategory.categoryID
WHERE (transactionProducts.productID='123' AND transactions.transactionDate='2017-01-12'
Group by transactionProducts.productID, transactionDate
UNION select * from "temptable" group by productID, productDesc, Sale, transactionDate 
ORDER BY transactionDate

Answer 1

使用not exists从临时表中选择结果集中尚不存在的行：

. . .
UNION ALL
SELECT tt.*
FROM temptable tt
WHERE NOT EXISTS (SELECT 1
                  FROM transactionproducts tp JOIN
                       transaction t
                       ON t.transactionID = tp.transactionID
                  WHERE tp.productId = tt.productId AND
                        t.transactionDate = tt.transactionDate
                 )
GROUP BY productID, productDesc, Sale, transactionDate 
ORDER BY transactionDate

Answer 2

这样如何：

SELECT transactionProducts.productID, products.productDesc, sum(salePrice) as Sale, transactionDate 
FROM products LEFT JOIN transactionProducts on products.productID = transactionProducts.productID 
LEFT JOIN transactions ON transactionProducts.transactionID = transactions.transactionID 
LEFT JOIN productCategory on productCategory.productID = products.productID 
LEFT JOIN categories on categories.categoryID = productCategory.categoryID
WHERE (transactionProducts.productID='123' AND transactions.transactionDate='2017-01-12' 
          AND sum(salePrice) > 0 )
Group by transactionProducts.productID, transactionDate
UNION select * from "temptable" group by productID, productDesc, Sale, transactionDate 
ORDER BY transactionDate

注意，我在第一个SELECT WHERE子句中添加了“AND sum(salePrice) >0”。

HTH