SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 2)
    Identifier t1.a (alias t1_a)
    Identifier t3.a (alias 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