Question

我所知道的唯一方法就是尴尬：

'check for empty return
Dim count As Integer = (From s In myEntity.employee Where employeeID = myEmployeeIDVariable).Count

'If there is a record, then process
If count > 0 Then
     Dim r = (From s In myEntity.employee Where employeeID = myEmployeeIDVariable).First()

     . . . do stuff . . .
End If

Answer 1

使用.FirstOrDefault（）。如果有第一条记录，您将获得第一条记录，如果没有返回记录，则返回null。

Answer 2

您可以将LINQ结果分配给变量并检查.Count（）是否为＆gt;这样你就不需要两次做同样的查询了。

代码：

'check for empty return
Dim r = (From s In myEntity.employee Where employeeID = myEmployeeIDVariable)

'If there is a record, then process
If r.Count() > 0 Then
  . . . do stuff . . .
End If

有没有一种很好的方法来检测Linq-To-Entities查询中的空结果？

2 个答案: