SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Function CAST (children 1)
     ExpressionList (children 2)
      Function if (children 1)
       ExpressionList (children 3)
        Function equals (children 1)
         ExpressionList (children 2)
          Identifier number
          Literal UInt64_999999
        Literal NULL
        Identifier number
      Literal \'UInt64\'
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier system.numbers
   Literal UInt64_10
