Error: String was not recognized as a valid DateTime

[JenHu]

Hi,

I have an asp.net web application,

I retrieve a stored session value from first page in 2nd page:

Dim AppFromDate1 As Object
If Session("FromDate1") Is DBNull.Value Then
AppFromDate1 = String.Empty
Else
AppFromDate1 = (Session("FromDate1"))
End If

When it's null string "", the run time value is ""{String}.

For inserting to the database, I set the parameter value as:

dbDetail.Parameters.Add(New SqlParameter("@AppFromDate1", SqlDbType.DateTime))

and I manage the value as :

Dim sqldatenull As SqlDateTime
sqldatenull = SqlDateTime.Null
If (AppFromDate1 = "") Then
dbDetail.Parameters("@AppFromDate1").Value = sqldatenull
Else
dbDetail.Parameters("@AppFromDate1").Value = DateTime.Parse(AppFromDate1)
End If


HOWEVER, dbDetail.Parameters("@AppFromDate1").Value = sqldatenull doesn't work, it still put the value to ""{string}, and the insert failed for an error:

"String was not recognized as a valid DateTime".

Please help!

[simonm]

Instead of setting your parameter value to SqlDateTime.Null, set it instead to System.DBNull.Value.

[JenHu]

Instead of setting your parameter value to SqlDateTime.Null, set it instead to System.DBNull.Value.

I still got error after I've changed my code to :

Dim sqldatenull As Object
sqldatenull = DBNull.Value
If (AppFromDate1 = "") Then
dbDetail.Parameters("@AppFromDate1").Value = sqldatenull
Else
dbDetail.Parameters("@AppFromDate1").Value = DateTime.Parse(AppFromDate1)
End If

I got error when it's inserting the value to database:
"String was not recognized as a valid DateTime"

Any suggestions?

[simonm]

This is what I mean:

dbDetail.Parameters("@AppFromDate1").Value = System.DBNull.Value

And I know this works fine for passing in NULL to SQL Server stored procedures because I have tested it here.

Presumably, the column in the table that you are inserting into allows nulls?