Hi,

I would just like to know what sql statement should I use to check if records Table A does not exists in any of the tables , Table B and Table C.
My idea is to use this

Select books
from table a
where a.books not exists = ((select b.books
from table b
where b.books = a.books)
or (select c.books
from table c
where c.books = a.books))

Thanks,

It depends ...
if tableB and tableC are small, try:

SELECT books
FROM tableA a
WHERE a.books NOT IN (SELECT books FROM tableB)
OR a.books NOT IN (SELECT books FROM tableC)


if tableB and tableC are medium or large, try:
SELECT books
FROM tableA a
WHERE NOT EXISTS (SELECT * FROM tableB B WHERE a.books = b.books)
OR NOT EXISTS (SELECT * FROM tableC C WHERE a.books = c.books)


you might also use a JOIN:

SELECT a.books
FROM tableA a
LEFT JOIN tableb B
ON a.books = b.books
LEFT JOIN tablec C
ON a.books = c.books
WHERE b.books IS NULL OR c.books IS NULL

Don't forget the UNION ALL option.