Дава ми следната грешка: Specified cast is not valid.
а това е кода, грешката е оцветена в червено.
Много ще съм благодарен ако ми обясните, защо става така.
string sql;
sql = "SELECT U.USER_ID, U.USER_NAME, U.RIGHTS AS USER_RIGHTS, IIF(G.RIGHTS, 1, 0) AS GROUP_RIGHTS";
sql = sql + " FROM ((USERS U LEFT JOIN GROUP_USERS GU ON U.USER_ID = GU.USER_ID) LEFT JOIN";
sql = sql + " GROUPS G ON G.GROUP_ID = GU.GROUP_ID) WHERE (U.USER_NAME = @USER_NAME) AND (U.[PASSWORD] = @PASSWORD)";
OleDbCommand aCommand = new OleDbCommand(sql, aConnection);
aConnection.Open();
OleDbParameter parametar = aCommand.CreateParameter();
parametar.ParameterName = "USER_NAME";
parametar.Value = username;
aCommand.Parameters.Add(parametar);
parametar = aCommand.CreateParameter();
parametar.ParameterName = "PASSWORD";
parametar.Value = password;
aCommand.Parameters.Add(parametar);
OleDbDataReader aReader = aCommand.ExecuteReader(CommandBehavior.CloseConnection);
while (aReader.Read())
{
if (userData_1 == null)
{
userData_1 = new UserData((int)aReader["USER_ID"], aReader["USER_NAME"].ToString(), (long)aReader["USER_RIGHTS"]);
}
if (aReader.IsDBNull(aReader.GetOrdinal("GROUP_RIGHTS")))
{
userData_1.ApplyRights((long)aReader["GROUP_RIGHTS"]);
}
}