Nhibernate 3.0 IQueryOver group by 满足条件的每组取一整条记录

Question

我的要求是获取 SiteItemOnHand 记录，按 Businessunitid、inventoryitemid 分组，并在具有 max(lastmodifiedtimestamp) 的每个组中获取整个 SiteItemOnHand 记录

我正在尝试为以下 sql 查询编写 nhibernate 等效查询

Select x.* from 
(
Select  businessunitid,inventoryitemid,max(lastmodifiedtimestamp) as maxvalue from InventoryItemBUOnHand  
group by businessunitid,inventoryitemid HAVING inventoryitemid in (939) and businessunitid=829
) as x
inner join
(
    Select  businessunitid,inventoryitemid,lastmodifiedtimestamp,inventoryitemonhandid from InventoryItemBUOnHand 
    where inventoryitemid in (939) and businessunitid=829
) as y
on x.businessunitid=y.businessunitid and  x.inventoryitemid =y.inventoryitemid and x.maxvalue=y.lastmodifiedtimestamp

我有很多限制。我只被允许使用 Nhibernate 3.0 版本，并且严格禁止编写 sql 查询（条件）。我只能写出下面查询的一半。任何帮助，将不胜感激。


var query= _session.QueryOver<SiteItemOnHand>()
      .Where(x => x.Businessunitid == siteID)
      .Where(x => x.End == endDate)
      .Where(x => x.CountID != filterCount.ID)
      .WhereRestrictionOn(x => x.ItemID).IsIn(itemIdList.ToArray())
      .SelectList(list => list
      .SelectMax(x => x.LastModifiedTimestamp)
      .SelectGroup(x => x.Businessunitid)
      .SelectGroup(x => x.ItemId));

上面的查询正在生成下面的 SQL 查询，其中只有 returns 三列，但我需要整个记录，因为在检索记录后我需要更新。我需要获取满足上述查询的所有 SiteItemOnHand 记录。

SELECT max(this_.lastmodifiedtimestamp) as y0_, this_.businessunitid as y1_, this_.inventoryitemid as y2_ 
FROM InventoryItemBUOnHand this_ 
WHERE this_.businessunitid = 567 and this_.enddate = '1/31/2019 1:18:17 AM' and not (this_.itemcountid = 958) 
and this_.inventoryitemid in (744,755)
GROUP BY this_.businessunitid, this_.inventoryitemid

如有任何帮助，我们将不胜感激。如果您需要更多信息，请告诉我。

Answer 1

如果我对你的理解正确的话，你有这样的数据并且你想要标记的记录。我不知道 iventoryitemonhandid 是否是 table 的 id，所以我不依赖于此。

Table InventoryItemBUOnHand (mapped as SiteItemOnHand)

| businessunitid|inventoryitemid|lastmodifiedtimestamp|inventoryitemonhandid|
|            829|            939|  2019-01-01 00:00:00|                  100| <--
|            829|            940|  2019-01-02 00:00:00|                  101| 
|            829|            940|  2019-01-03 00:00:00|                  102| <-- 
|            829|            950|  2019-01-04 00:00:00|                  103| 
|            829|            950|  2019-01-10 00:00:00|                  104| <--
|            829|            950|  2019-01-06 00:00:00|                  105|

如果是，那么我会像这个问题一样使用子查询： SO: NHibernate - Select full records from aggregates

根据您的要求修改（未测试）它看起来像这样：

int siteID = 829;
List<int> itemIdList = new List<int>() { 939, 940, 950 };
SiteItemOnHand siAlias = null;

var subQuery = QueryOver.Of<SiteItemOnHand>()
    .Where(x => x.Businessunitid == siAlias.Businessunitid)
    .And(x => x.ItemID == siAlias.ItemID)
    .Select(Projections.Max<SiteItemOnHand>(y => y.lastmodifiedtimestamp));

var siteItems = Session.QueryOver<SiteItemOnHand>(() => siAlias)
    .Where(x => x.Businessunitid == siteID)
    .AndRestrictionOn(x => x.ItemID).IsIn(itemIdList.ToArray())
    .WithSubquery.Where(x => siAlias.lastmodifiedtimestamp == subQuery.As<DateTime>())
    .List();

这里的目标是使用子查询来过滤每个组的正确最大日期，然后使用它来过滤实际记录。

结果 SQL 看起来像这样：

SELECT <field_list> FROM InventoryItemBUOnHand 
WHERE Businessunitid = 829
AND inventoryitemid in (939, 940, 950)
AND this_.lastmodifiedtimestamp = 
   (SELECT max(this_0_.lastmodifiedtimestamp) as y0_ 
       FROM InventoryItemBUOnHand this_0_ 
       WHERE this_0_.Businessunitid = this_.Businessunitid and this_0_.ItemID = this_.ItemID)

警告： 当两个记录具有相同的 businessunitid 和 inventoryitemid 的相同值时，比较 lastmodifiedtimestamp 可能会导致不需要的结果。如果发生这种情况，您可以仅在第一条记录中添加 OrderBy 和 select。如果 inventoryitemonhandid 是唯一索引，它会变得更加简单。

Nhibernate 3.0 IQueryOver group by 满足条件的每组取一整条记录

Nhibernate 3.0 IQueryOver group by and fetch one entire record in each group which satisfy the condition

c#

linq

nhibernate

queryover