Sql 如何确定客户历史记录的第一条记录中的单元格是否包含值？

我有一个Tickets表，可以保存数年的客户数据。我试图确定一位已经访问x次的客户是否在第一次访问时使用了优惠券。我有这个（下面的SQL），我正在使用，以便我可以打破我寻找的组。我真正想知道的是，他们中有多少人在第一次访问（最早的销售日期）时使用了优惠券

作为最终结果，我只需要一个计数，不需要查看CustomerID、SaleDate等，我只需要一个（伪）选择计数（CustomerID），其中TotalCouples单元格上有一个值，它是该CustomerID的最早记录

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我想我必须添加一个RowID并使用Where-RowID=1，但我不确定如何将其应用到我所做的工作中

您可以使用

行号（）

确定首次就诊，然后使用条件聚合。以下内容获取具有该标志的组中的客户：

WITH T AS (
      SELECT CustomerId, SaleDate, TotalCoupons,
             COUNT(*) OVER (PARTITION BY CustomerID) as Cnt,
             ROW_NUMBER() OVER (PARTITION BY CustomerID ORDER BY SaleDate) as seqnum
      FROM Store.dbo.Tickets
      Where (CreationDate between '2014-01-01' and '2014-11-12') and
            (IsDeleted = 0) and
            (TicketStatus = 'Complete')
     )
SELECT CustomerID, SaleDate, TotalCoupons, Cnt,
       MAX(CASE WHEN seqnum = 1 and TotalCoupons IS NOT NULL) as HasCouponFirstVisit              
FROM T
WHERE Cnt = 10;

您可以通过执行以下操作来计算它们的数量：

WITH T AS (
      SELECT CustomerId, SaleDate, TotalCoupons,
             COUNT(*) OVER (PARTITION BY CustomerID) as Cnt,
             ROW_NUMBER() OVER (PARTITION BY CustomerID ORDER BY SaleDate) as seqnum
      FROM Store.dbo.Tickets
      Where (CreationDate between '2014-01-01' and '2014-11-12') and
            (IsDeleted = 0) and
            (TicketStatus = 'Complete')
     )
SELECT COUNT(CustomerID)
FROM T
WHERE Cnt = 10 AND seqnum = 1 AND TotalCoupons IS NOT NULL;

我不确定你要找的是不是

totalcoups不为空

，但它应该足够接近

WITH T AS (
      SELECT CustomerId, SaleDate, TotalCoupons,
             COUNT(*) OVER (PARTITION BY CustomerID) as Cnt,
             ROW_NUMBER() OVER (PARTITION BY CustomerID ORDER BY SaleDate) as seqnum
      FROM Store.dbo.Tickets
      Where (CreationDate between '2014-01-01' and '2014-11-12') and
            (IsDeleted = 0) and
            (TicketStatus = 'Complete')
     )
SELECT COUNT(CustomerID)
FROM T
WHERE Cnt = 10 AND seqnum = 1 AND TotalCoupons IS NOT NULL;