My application outputs DBNull but in the database it isn't DBNull - mysql

Question

My application outputs "System.InvalidCastException: "Object cannot be cast from DBNull to other types."
Dim sqlquery = String.Format("SELECT id, date, film, start_time, end_time, participants_count, confirmed FROM calendar WHERE id='" & id & "'")
connection.Open()
With command
.Connection = connection
.CommandText = sqlquery
End With
dataadapter.SelectCommand = command
dataadapter.Fill(datatable)
id = Convert.ToInt32(datatable.Rows(0).Item("id"))
Dim date_ As String = datatable.Rows(0).Item("date").ToString
Dim film As String = datatable.Rows(0).Item("film").ToString
Dim start_time As String = datatable.Rows(0).Item("start_time").ToString
Dim end_time As String = datatable.Rows(0).Item("end_time").ToString
Dim participants_count As Integer = Convert.ToInt32(datatable.Rows(0).Item("participants_count"))
Dim confirmed As Integer = Convert.ToInt32(datatable.Rows(0).Item("confirmed"))
The problem arises there: "participants_count" and "confirmed". All the other columns are working perfectly. In the database these two columns aren't DBNull: Picture of the real MySQL-Result. They can't even be DBNull: MySQL Structure
If I output the value of both with a MessageBox it also contains nothing.
I would be very grateful if I became a solution.
Julius

Answer 1

Dim participants_count As Integer
Integer.TryParse(datatable.Rows(0).Item("participants_count").Tostring, participants_count)
This will attempt to convert it to an Integer and returns 0 if it fails otherwise it will set the value to participants_count. This should help with the DBNull issue. You can do this with the confirmed field to.

Answer 2

You can get the query results without using a DataTable. That way you can be exact about the data types and so there is less chance of something unexpected happening:
Dim connStr = "your connection string"
Dim sql = "SELECT `id`, `date`, `film`, `start_time`, `end_time`, `participants_count`, `confirmed` FROM `calendar` WHERE `id` = #id"
Dim id = "2"
Dim date_ As DateTime
Dim start_time As TimeSpan
Dim end_time As TimeSpan
Dim participants_count As Integer
Dim confirmed As Boolean
Using conn As New MySqlConnection(connStr)
Using cmd As New MySqlCommand(sql, conn)
cmd.Parameters.Add(New MySqlParameter With {
.ParameterName = "#id",
.MySqlDbType = MySqlDbType.VarChar,
.Size = 8,
.Value = id})
conn.Open()
Dim rdr = cmd.ExecuteReader()
If rdr.HasRows Then
date_ = rdr.GetDateTime(1)
start_time = rdr.GetTimeSpan(3)
end_time = rdr.GetTimeSpan(4)
participants_count = rdr.GetInt16(5)
confirmed = rdr.GetBoolean(6)
End If
conn.Close()
End Using
End Using
The SQL parameter should have its .MySqlDbType and .Size set to match the id column in the database. The rdr.Get... functions should be chosen to match the types from the database.