Question

我几天前就开始学习SQL了，我接下来的查询在“案例”附近给出了一个错误，我似乎无法弄明白：

SELECT * , Stuff((SELECT ', ' +  CAST( orderid as varchar(10))
      FROM( oitems t2 
 case when (ocardtype in ('PayPal','Sofort') OR
        ocardtype in ('mastercard','visa') and
        odate is not null) then 
              FOR XML PATH(''), 1, 2, '') [Proccessed] else  FOR XML PATH(''), 1, 2, '') [NotProccessed] end)
                      FROM orders t1
    Group by orderid,t1.odate, t1.ocardtype

我想你得到了这段代码应该做的，但我不确定这是否是使用select case的正确方法。

oitems table

+---------+-----------+----------+
| orderid | catalogid | numitems |
+---------+-----------+----------+
| o737    |       353 |        1 |
| o738    |       364 |        4 |
| o739    |       353 |        3 |
| o740    |       364 |        6 |
| o741    |       882 |        2 |
| o742    |       224 |        5 |
| o743    |       224 |        2 |
+---------+-----------+----------+






orders table
    +-----------------+------------+------------+
    |         orderid | ocardtype  |   odate    |
    +-----------------+------------+------------+
    |     o737        | Paypal     |            | 'OK
    |     o738        | MasterCard | 01.02.2012 | 'OK
    |     o739        | MasterCard | 02.02.2012 | 'OK
    |     o740        | Visa       | 03.02.2012 | 'OK
    |     o741        | Sofort     |            | 'OK
    |     o742        |            |            | 'ignore because ocardtype is empty
    |     o743        | MasterCard |            | 'ignore because Mastercard no odate
    +-----------------+------------+------------+

预期结果

+-----------+------------------------+--------------+
| catalogid | ProcessedSucssessfully | NotProcessed |
+-----------+------------------------+--------------+
|       353 |o737,o739               |              |
|       364 |o738,o740               |              |
|       882 |o741                    |              |
|       224 |                        |o742,o743     |
+-----------+------------------------+--------------+

我有以下条件，您可以在上述代码的案例陈述中找到

如果ocardtype为空，则将orderid添加到NotProcessed
如果某个订单的ocardtype为万事达卡或维萨而且odate为空，则将orderid添加到NotProcessed
如果ocardtype是Paypal或Sofort，则不要检查odate并将orderid添加到ProcessedSucssessfully

Answer 1

检查此请求

SELECT CatalogId, ProcessedSucssessfully = 
       STUFF((SELECT ', ' + b.OrderId
              FROM oitmes b JOIN orders o ON b.OrderId = o.OrderId
              WHERE b.CatalogId = a.CatalogId
              AND (o.OcardtType in ('PayPal','Sofort') OR o.OcardtType in  ('mastercard','visa') and o.odate is not null)    
              FOR XML PATH('')), 1, 2, ''),
                  NotProcessed =
        STUFF((SELECT ', ' + c.OrderId
               FROM oitmes c JOIN orders o ON c.OrderId = o.OrderId
               WHERE c.CatalogId = a.CatalogId
               AND (o.OcardtType in ('mastercard') OR o.OcardtType is null) and o.odate is null
               FOR XML PATH('')), 1, 2, '')
FROM oitmes a
GROUP BY a.CatalogId

SQLFiddle上的演示

Answer 2

您似乎在FROM之前使用CASE子句而不是之后：

SELECT   ProductNumber, Category =
      CASE ProductLine
         WHEN 'R' THEN 'Road'
         WHEN 'M' THEN 'Mountain'
         WHEN 'T' THEN 'Touring'
         WHEN 'S' THEN 'Other sale items'
         ELSE 'Not for sale'
      END,
   Name
FROM Production.Product
ORDER BY ProductNumber

我能想到的其他事情是你没有使用CASE返回true或false，这可能会让你犯错误。

选择情况下的语法错误

2 个答案: