private string BuildSql()
{
if (string.IsNullOrWhiteSpace(Table))
{
throw new InvalidOperationException("table name is missing");
}
if (FieldNames.Count == 0)
{
throw new InvalidOperationException("field names are missing");
}
return(new StringBuilder()
.AppendInsert(Table, TemporaryTable, FieldNames, OutputFields)
.Append(" ")
.Append(SelectCommand.Build().CommandText)
.ToString());
}