private AggregateColumn(AggregateColumn column, int newIndex)
     : base(column.Name, newIndex, column.Type, column)
 {
     AggregateType = column.AggregateType;
     SourceIndex   = column.SourceIndex;
 }
 private AggregateColumn(AggregateColumn column, string newName)
     : base(newName, column.Index, column.Type, column)
 {
     AggregateType = column.AggregateType;
     SourceIndex   = column.SourceIndex;
 }