SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Identifier t2.a
   TablesInSelectQuery (children 2)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      Subquery (alias t1) (children 1)
       SelectWithUnionQuery (children 1)
        ExpressionList (children 1)
         SelectQuery (children 2)
          ExpressionList (children 1)
           Identifier x (alias a)
          TablesInSelectQuery (children 1)
           TablesInSelectQueryElement (children 1)
            TableExpression (children 1)
             TableIdentifier t1
    TablesInSelectQueryElement (children 2)
     TableExpression (children 1)
      Subquery (alias t2) (children 1)
       SelectWithUnionQuery (children 1)
        ExpressionList (children 1)
         SelectQuery (children 2)
          ExpressionList (children 1)
           Identifier x (alias a)
          TablesInSelectQuery (children 1)
           TablesInSelectQueryElement (children 1)
            TableExpression (children 1)
             TableIdentifier t1
     TableJoin (children 1)
      Function equals (children 1)
       ExpressionList (children 2)
        Identifier t1.a
        Identifier t2.a
   ExpressionList (children 1)
    Identifier t1.a
