CreateQuery clear_column (children 3)
 Identifier clear_column
 Columns definition (children 1)
  ExpressionList (children 3)
   ColumnDeclaration d (children 1)
    DataType Date
   ColumnDeclaration num (children 1)
    DataType Int64
   ColumnDeclaration str (children 1)
    DataType String
 Storage definition (children 4)
  Function MergeTree
  Function toYYYYMM (children 1)
   ExpressionList (children 1)
    Identifier d
  Identifier d
  Set
