SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 2)
    WithElement (children 1)
     Subquery (children 1)
      SelectWithUnionQuery (children 1)
       ExpressionList (children 1)
        SelectQuery (children 1)
         ExpressionList (children 2)
          Literal UInt64_0 (alias key)
          Literal \'a\' (alias acol)
    WithElement (children 1)
     Subquery (children 1)
      SelectWithUnionQuery (children 1)
       ExpressionList (children 1)
        SelectQuery (children 1)
         ExpressionList (children 1)
          Literal UInt64_2 (alias key)
   ExpressionList (children 1)
    Identifier a.key
   TablesInSelectQuery (children 3)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier b
    TablesInSelectQueryElement (children 2)
     TableExpression (children 1)
      TableIdentifier a
     TableJoin (children 1)
      Literal UInt64_1
    TablesInSelectQueryElement (children 2)
     TableExpression (children 1)
      TableIdentifier a (alias a1)
     TableJoin (children 1)
      Literal UInt64_1
