HQL預期加入路徑（加入同一張表時）

Question

我試圖獲得兩個不同設備的測量對，加入時間戳相同。在SQL中，此按預期工作：

select 
    leftItem.Timestamp, leftItem.Value, rightItem.Value 
from 
    DataTable leftItem 
    inner join DataTable rightItem 
    on leftItem.Timestamp = rightItem.Timestamp 
where 
    leftItem.Device = 1 and rightItem.Device = 2 

但如果我嘗試將其轉換爲HQL：

select 
    left, right 
from 
    DataTable as left 
    inner join DataTable as right 
    on left.Timestamp = right.Timestamp 
where 
    left.Device = 1 and right.Device = 2 

我得到一個NHibernate.Hql.Ast.ANTLR.SemanticException:

 
Path expected for join! 

如何指定一個「路徑「到同一張桌子？

Answer 1

在HQL中，只能對實體之間的關聯進行連接。如果你想在別的東西加入，唯一的可能性就是讓在加入where子句：

select left, right 
from 
    DataTable as left, DataTable as right 
where 
    left.Timestamp = right.Timestamp 
    and left.Device = 1 
    and right.Device = 2