SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 2)
    Identifier t1.a
    Identifier t3.a
   TablesInSelectQuery (children 2)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier t1
    TablesInSelectQueryElement (children 2)
     TableExpression (children 1)
      TableIdentifier t3
     TableJoin (children 1)
      Function equals (children 1)
       ExpressionList (children 2)
        Identifier t1.a
        Identifier t3.a