Query Parameter Value Is Null When Enum Item 0 is Cast with Int32
- by Timothy
When I use the first item in a zero-based Enum cast to Int32 as a query parameter, the parameter value is null. I've worked around it by simply setting the first item to a value of 1, but I was wondering though what's really going on here? This one has me scratching my head. Why is the parameter value regarded as null, instead of 0?
Enum LogEventType : int
{
SignIn,
SignInFailure,
SignOut,
...
}
private static DataTable QueryEventLogSession(DateTime start, DateTime stop)
{
DataTable entries = new DataTable();
using (FbConnection conn = new FbConnection(DSN))
{
using (FbDataAdapter adapter = new FbDataAdapter(
"SELECT event_type, event_timestamp, event_details FROM event_log " +
"WHERE event_timestamp BETWEEN @start AND @stop " +
"AND event_type IN (@signIn, @signInFailure, @signOut) " +
"ORDER BY event_timestamp ASC", conn))
{
adapter.SelectCommand.Parameters.AddRange(new Object[] {
new FbParameter("@start", start),
new FbParameter("@stop", stop),
new FbParameter("@signIn", (Int32)LogEventType.SignIn),
new FbParameter("@signInFailure", (Int32)LogEventType.SignInFailure),
new FbParameter("@signOut", (Int32)LogEventType.SignOut)});
Trace.WriteLine(adapter.SelectCommand.CommandText);
foreach (FbParameter p in adapter.SelectCommand.Parameters)
{
Trace.WriteLine(p.Value.ToString());
}
adapter.Fill(entries);
}
}
return entries;
}
