SELECT round(DATACZAS) AS "data", decode(ID_RYBY, NULL, 'Nie ma informacji', id_ryby) AS "numer",
ID_RYBY,Decode(ID_RYBY,1,'Karp',3,'Leszcz',9,'Szczupak',10,'Sandacz',NULL,'Brak polowu','Inny gatunek') AS "ryba"
FROM rejestr WHERE ID_RYBY IN (1,3,9,10) OR ID_RYBY IS NULL;

SELECT round(DATACZAS) AS "data", decode(ID_RYBY, NULL, 'Nie ma informacji', id_ryby) AS "numer",
nvl(nazwa,'Brak polowu') AS "typ ryby"
FROM rejestr LEFT JOIN ryba USING(ID_RYBY) WHERE ID_RYBY IN (1,3,9,10) OR ID_RYBY IS NULL ORDER BY 1;