SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 1)
    ColumnsRegexpMatcher
   TablesInSelectQuery (children 3)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      Subquery (alias a) (children 1)
       SelectWithUnionQuery (children 1)
        ExpressionList (children 1)
         SelectQuery (children 1)
          ExpressionList (children 2)
           Literal UInt64_1 (alias id)
           Literal \'a\' (alias test)
    TablesInSelectQueryElement (children 2)
     TableExpression (children 1)
      Subquery (alias b) (children 1)
       SelectWithUnionQuery (children 1)
        ExpressionList (children 1)
         SelectQuery (children 1)
          ExpressionList (children 2)
           Literal UInt64_1 (alias id)
           Literal \'b\' (alias test)
     TableJoin (children 1)
      Function equals (children 1)
       ExpressionList (children 2)
        Identifier b.id
        Identifier a.id
    TablesInSelectQueryElement (children 2)
     TableExpression (children 1)
      Subquery (alias c) (children 1)
       SelectWithUnionQuery (children 1)
        ExpressionList (children 1)
         SelectQuery (children 1)
          ExpressionList (children 2)
           Literal UInt64_1 (alias id)
           Literal \'c\' (alias test)
     TableJoin (children 1)
      Function equals (children 1)
       ExpressionList (children 2)
        Identifier c.id
        Identifier a.id
