SQL 选择案例

Question

我有以下 sql 表

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
+-----------------+------------+------------+

名为result的reusltant数据表

 +-----------+----------+--------------+
| catalogid | numitems | ignoreditems |
+-----------+----------+--------------+
|       353 |        4 |            0 |
|       364 |       10 |            0 |
|       882 |        2 |            0 |
|       224 |        0 |            7 |
+-----------+----------+--------------+

想法是对具有相同catalogid 的产品的numitems 列求和，具体取决于oitems 表中的数据，条件如下

1. 如果ocardtype 为空，则忽略numitems 并考虑它 作为 0 在 sum 和 sum 忽略的项目到 ignoreditems 列
2. 如果某个订单的ocardtype 是MasterCard 或Visa 并且 odate 为空然后忽略 numitems 并将其视为 0 并将忽略的项目汇总到 ignoreditems 列
3. 如果ocardtype 是Paypal 或Sofort，那么只需执行numitems 和 不检查日期，因为这些类型不需要odate

基本上我想将结果数据表保存到临时数据表并将其加载到 vb.net 数据表中

我很难弄清楚如何在 sql 查询中执行此操作！我需要这个作为 vb.net 的 sql 命令，能够使用循环和大量检查的 vb.net 数据表以编程方式完成它 使用 linq 是一种选择，但我只需要从服务器获取它

Answer 1

select catalogid, numitems, allitems - numitems ignoreditems
from (
  select i.catalogid,
    sum(case when (ocardtype in ('PayPal','Sofort') OR
                   ocardtype in ('mastercard','visa') and
                   odate is not null) AND NOT EXISTS (
                     select * from booked b
                     where b.ignoredoid = o.orderid
                   ) then numitems
                   else 0 end) numitems,
    sum(numitems) allitems
  from orders o
  join oitems i on i.orderid=o.orderid
  group by i.catalogid
) X

Answer 2

类似：

SELECT
     oi.catalog_id,
     SUM(CASE
            WHEN ocardtype in ('Paypal','Sofort') THEN numitems
            WHEN ocardtype in ('Mastercard','Visa') and odate is not null THEN numitems
            ELSE 0 END) as numitems,
     SUM(CASE
            WHEN ocardtype is null then numitems
            WHEN ocardtype in ('Mastercard','Visa') and odate is null THEN numitems
            ELSE 0 END) as ignoreditems
FROM
   oitems oi
      inner join
   Orders o
      on
         oi.orderid = o.orderid
GROUP BY
   oi.catalog_id

（假设您在叙述中使用了“空”一词，则表示该列是NULL）

Answer 3

这是您原始请求的 Linq-to-sql 版本（作为 LINQpad 查询）：

Dim odateRequired = {"MasterCard", "Visa"}
Dim odateNotRequired = {"Paypal", "Sofort"}
Dim result = From o In Orders Join i In Oitems On o.orderid Equals i.orderid _
             Let check = o.ocardtype IsNot Nothing _
                     AndAlso ((odateRequired.Contains(o.ocardtype) _
                               AndAlso o.odate IsNot Nothing) _
                        OrElse odateNotRequired.Contains(o.ocardtype)) _
         Group By i.catalogid Into _
         numitem = Sum(If(check, i.numitems, 0)), _
         ignored = Sum(If(check, 0, i.numitems))

result.Dump

您在 cmets 中对 RichardTheKiwi 的回答的额外要求（它只包括 check 前面的 Not (From b In Bookeds Where b.ignoredoid=i.orderid).Any AndAlso）：

Dim odateRequired = {"MasterCard", "Visa"}
Dim odateNotRequired = {"Paypal", "Sofort"}
Dim result = From o In Orders Join i In Oitems On o.orderid Equals i.orderid _
             Let check = Not (From b In Bookeds Where b.ignoredoid = i.orderid).Any _
                     AndAlso o.ocardtype IsNot Nothing _
                     AndAlso ((odateRequired.Contains(o.ocardtype) _
                               AndAlso o.odate IsNot Nothing) _
                        OrElse odateNotRequired.Contains(o.ocardtype)) _
         Group By i.catalogid Into _
         numitem = Sum(If(check, i.numitems, 0)), _
         ignored = Sum(If(check, 0, i.numitems))

result.Dump