CreateQuery null_subcolumns (children 3)
 Identifier null_subcolumns
 Columns definition (children 1)
  ExpressionList (children 2)
   ColumnDeclaration id (children 1)
    DataType UInt32
   ColumnDeclaration n (children 1)
    DataType Nullable (children 1)
     ExpressionList (children 1)
      DataType String
 Storage definition (children 2)
  Function MergeTree
  Identifier id