SelectWithUnionQuery (children 2)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Function if (alias not_existing) (children 1)
     ExpressionList (children 3)
      Subquery (children 1)
       SelectWithUnionQuery (children 1)
        ExpressionList (children 1)
         SelectQuery (children 1)
          ExpressionList (children 1)
           Function hasColumnInTable (children 1)
            ExpressionList (children 3)
             Literal \'system\'
             Literal \'numbers\'
             Literal \'not_existing\'
      Identifier not_existing
      Literal UInt64_42
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier system.numbers
   Literal UInt64_1
 Identifier TSKV
