使用Restrictions.Discjunction进行投影

Question

使用Restrictions.Discjunction()或Restrictions.Or()进行投影将生成WHERE子句而不是HAVING子句。这将导致错误( WHERE子句不能引用聚合表达式)。

示例：

.CreateCriteria(typeof(SalesOrderLine), "SOL")
.CreateCriteria("DeliveryOrderLines", "DOL", JoinType.LeftOuterJoin)
.SetProjection(
    Projections.GroupProperty("SOL.Key").As("SalesOrderLineId"),
    Projections.GroupProperty("SOL.Item"),
    Projections.GroupProperty("SOL.Description"),
    Projections.GroupProperty("SOL.UnitPrice"),
    Projections.GroupProperty("SOL.Quantity"),
    Projections.GroupProperty("SOL.DiscountPercentage"),
    Projections.GroupProperty("SOL.SalesOrder"))
.Add(Restrictions.Or(
    Restrictions.IsNull(Projections.Sum("DOL.Quantity")),
    Restrictions.GtProperty("SOL.Quantity", Projections.Sum("DOL.Quantity")))), 
.List();

SQL结果：

SELECT this_.SalesOrderLineId as y0_, this_.Item as y1_, this_.Description as y2_, this_.UnitPrice as y3_, this_.Quantity as y4_, this_.DiscountPercentage as y5_, this_.SalesOrderId as y6_ FROM SalesOrderLine this_ left outer join DeliveryOrderLine dol1_ on this_.SalesOrderLineId=dol1_.SalesOrderLineId 
WHERE (sum(dol1_.Quantity) is null or this_.Quantity > sum(dol1_.Quantity))
GROUP BY this_.SalesOrderLineId, this_.Item, this_.Description, this_.UnitPrice, this_.Quantity, this_.DiscountPercentage, this_.SalesOrderId

我做错了吗？或者这是Nhibernate 3.1中的一个bug？

提前感谢:)。

Answer 1

上次我检查条件API不支持HAVING子句。您将需要使用HQL，它确实支持具有。

要使用Criteria API，您必须将查询修改为：

SELECT this_.SalesOrderLineId as y0_, this_.Item as y1_, this_.Description as y2_, this_.UnitPrice as y3_, this_.Quantity as y4_, this_.DiscountPercentage as y5_, this_.SalesOrderId as y6_ FROM SalesOrderLine this_ left outer join DeliveryOrderLine dol1_ on this_.SalesOrderLineId=dol1_.SalesOrderLineId 
WHERE (select sum(Quantity) from DeliveryOrderLine) is null or (select sum(Quantity) from > SalesOrderLine ) > (select sum(Quantity) from DeliveryOrderLine)
GROUP BY this_.SalesOrderLineId, this_.Item, this_.Description, this_.UnitPrice, this_.Quantity, this_.DiscountPercentage, this_.SalesOrderId

我给出的解决方案会因为多次求和计算而对性能造成一些影响，但它会完成工作。

您也可以尝试这样做，但我不确定它是否能正确运行：

SELECT this_.SalesOrderLineId as y0_, this_.Item as y1_, this_.Description as y2_, this_.UnitPrice as y3_, this_.Quantity as y4_, this_.DiscountPercentage as y5_, this_.SalesOrderId as y6_, SUM(dol1_Quantity) as sum1, SUM(this_.Quantity) as sum2 from SalesOrderLine this_ left outer join DeliveryOrderLine dol1_ on this_.SalesOrderLineId=dol1_.SalesOrderLineId 
WHERE sum1 is null or sum1 > sum2
GROUP BY this_.SalesOrderLineId, this_.Item, this_.Description, this_.UnitPrice, this_.Quantity, this_.DiscountPercentage, this_.SalesOrderId

希望这能有所帮助！