LINQ to SQL中的转换无效

Question

我已经使用LINQ to SQL引发无效的转换异常。这是我在C＃类：

[Table(Name = "tbl_request$")] 
public class request 
{ 
    [Column(IsPrimaryKey = true)] 
    public float requestID; 
    [Column] 
    public string moduleCode; 
    [Column] 
    public float park; 
    [Column] 
    public string requestedRoom; 
    [Column] 
    public float week; 
    [Column] 
    public float day; 
    [Column] 
    public float period; 
    [Column] 
    public float status; 
    [Column] 
    public float semester; 
    [Column] 
    public float priority; 
    [Column] 
    public float adhoc; 
    [Column] 
    public float numStudents; 
    [Column] 
    public float collectionID; 
    [Column] 
    public float roomCount; 
} 

数据库表这相当于

requestID float Unchecked 
moduleCode nvarchar(255) Checked 
park float Checked 
requestedRoom nvarchar(255) Checked 
week float Checked 
day float Checked 
period float Checked 
status float Checked 
semester float Checked 
priority float Checked 
adhoc float Checked 
numStudents float Checked 
collectionID float Checked 
roomCount float Checked 

一切看起来好像没什么问题。还有其他建议吗？

Specified cast is not valid. 

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.InvalidCastException: Specified cast is not valid. 

Source Error: 

Line 12:    var bookingtable = Database.DatabaseContext.GetTable<Database.request>(); 
Line 13:    var dict = new System.Collections.Generic.Dictionary<int, System.Collections.Generic.List<Database.request>>(); 
Line 14:    foreach (var request in bookingtable) 
Line 15:    { 
Line 16:     if (dict[(int)request.collectionID] == null) 

堆栈跟踪深入LINQ内部。

Answer 1

原来，C＃想要一个double?而不是float?，即使DB类型是FLOAT。