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  • T-SQL :联接查询练习 (杂)

    1.每个客户返回一行订单 日期在~到~之间

    SELECT E.empid,
      DATEADD(day, D.n - 1, '20090612') AS dt
    FROM HR.Employees AS E
      CROSS JOIN Nums AS D
    WHERE D.n <= DATEDIFF(day, '20090612', '20090616') + 1
    ORDER BY empid, dt;

    2.返回美国客户 并返回订单数量和总数量

    SELECT C.custid, COUNT(DISTINCT O.orderid) AS numorders, SUM(OD.qty) AS totalqty
    FROM Sales.Customers AS C
      JOIN Sales.Orders AS O
        ON O.custid = C.custid
      JOIN Sales.OrderDetails AS OD
        ON OD.orderid = O.orderid
    WHERE C.country = N'USA'
    GROUP BY C.custid;

    3.返回 某个时间段 下单的用户以及订单 还要同时返回 在该时间段 没有下单的用户

    SELECT C.custid, C.companyname, O.orderid, O.orderdate
    FROM Sales.Customers AS C
      LEFT OUTER JOIN Sales.Orders AS O
        ON O.custid = C.custid
        AND O.orderdate = '20070212';

    4.返回某个时间段用户是否有订单

    SELECT DISTINCT C.custid, C.companyname, 
      CASE WHEN O.orderid IS NOT NULL THEN 'Yes' ELSE 'No' END AS [HasOrderOn20070212]
    FROM Sales.Customers AS C
      LEFT OUTER JOIN Sales.Orders AS O
        ON O.custid = C.custid
        AND O.orderdate = '20070212';
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  • 原文地址:https://www.cnblogs.com/feizianquan/p/9359270.html
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