mysql - select the extra row data -

this table sample, had deleted lot column.

id  orid    to_id   seq 1   1       5       a12 2   2       6       a12 3   3       7       a12 4   4       _       a12 <--- want find row 5   5       _       a13 6   6       _       a13 7   7       _       a13 

i want find data. want use 2 sql find data.

(select * forgerock seq = 'a13') (select * forgerock seq != 'a13') b 

i had tried it, not wanted. how can it? thanks.

select b.*    (select * forgerock seq = 'a13') right join    (select * forgerock seq != 'a13') b on a.to_id = b.to_id; 

this sqlfiddle

i guessing want find rows have no connection row.

select fr.* forgerock fr fr.to_id null ,       not exists (select 1                   forgerock fr2                   fr.from_id = fr2.to_id                  );