使用时间字段选择第一次出现的具有今天日期的记录

Question

我有一个表，其中每个记录都有一个 date 字段和一个 time(7) 字段。将记录插入数据库后，它将记录插入日的日期和插入时间。

现在我想从Table1 INNER JOIN Table2 中选择今天第一次出现的所有记录，因为这些记录可以重复。我尝试使用time(7) 字段选择今天日期中record1 = 'ABC' 的最少时间，但这不会返回任何结果，我确信查询应该返回 1 个结果，因为它以不同的时间记录了两次，但与今天的日期。如何选择第一次出现今天日期的产品？

示例：

SELECT ProductName, Description, Quantity,
FROM Products
INNER JOIN Transactions
    ON Products.ProductID = Transactions.ProductID
WHERE Transactions.ProductID = 'A6612'
    AND CONVERT(VARCHAR(20), `Transactions.Date_Tracked, 103) = CONVERT(VARCHAR(10), getdate(), 103)
    AND Time_Tracked = (
        SELECT min(Time_Tracked)
        FROM Transactions
        )
    AND Country = 'United States'

Answer 1

将选项与 EXISTS 运算符一起使用。此外，您可以避免使用 CAST 函数而不是 CONVERT into VARCHAR 数据类型的无效条件（或谓词）

SELECT p.ProductName, p.Description, p.Quantity
FROM Products p INNER JOIN Transactions t ON p.ProductID = t.ProductID
WHERE t.ProductID = 'A6612' 
  AND CAST(t.Date_Tracked AS date) = CAST(GETDATE() AS date)
  AND EXISTS (                      
              SELECT 1
              FROM Transactions t2
              WHERE t.ProductID = t2.ProductID
                AND CAST(t2.Date_Tracked AS date) = CAST(GETDATE() AS date)
              HAVING MIN(t2.Time_Tracked) = t.Time_Tracked                      
              ) 
  AND Country = 'United States'

如果请求返回一条记录，只需在 TOP 子句中使用 ORDER BY 子句即可。

SELECT TOP 1 p.ProductName, p.Description, p.Quantity
FROM Products p INNER JOIN Transactions t ON p.ProductID = t.ProductID
WHERE t.ProductID = 'A6612' 
  AND CAST(t.Date_Tracked AS date) = CAST(GETDATE() AS date)
  AND p.Country = 'United States'
ORDER BY t.Time_Tracked

最后，如果 Date_Tracked 的类型为 datetime，那么：

SELECT TOP 1 p.ProductName, p.Description, p.Quantity
FROM Products p INNER JOIN Transactions t ON p.ProductID = t.ProductID
WHERE t.ProductID = 'A6612' 
  AND CAST(t.Date_Tracked AS date) = CAST(GETDATE() AS date)
  AND p.Country = 'United States'
ORDER BY CAST(t.Date_Tracked AS time)

Answer 2

您尝试过使用 rowid 吗？

SELECT ProductName, Description, Quantity,
FROM Products
INNER JOIN Transactions
    ON Products.ProductID = Transactions.ProductID
WHERE Transactions.ProductID = 'A6612'
    AND CONVERT(VARCHAR(20), `Transactions.Date_Tracked, 103) = CONVERT(VARCHAR(10), getdate(), 103)
    AND Transactions.rowid = (SELECT min(rowid)
        FROM Transactions group by productid,date) --This will give you the minimum rowid 
    AND Country = 'United States'                    --grouped by productid and date.  

Answer 3

你的查询应该是这样的，

SELECT ProductName, Description, Quantity,
FROM Products
INNER JOIN Transactions
    ON Products.ProductID = Transactions.ProductID
WHERE Transactions.ProductID = 'A6612'
    AND CONVERT(VARCHAR(20), Transactions.Date_Tracked, 103) = CONVERT(VARCHAR(10), getdate(), 103)
    AND Time_Tracked = (
        SELECT min(Time_Tracked)
        FROM Transactions
        WHERE CONVERT(VARCHAR(20), Transactions.Date_Tracked, 103) = CONVERT(VARCHAR(10), getdate(), 103)
        )
    AND Country = 'United States'