Question

If I have a list of items, say

apples pairs pomegranites 

and I want to identify any that don’t exist in the ‘fruit’ column in an SQL DB table.

• Fast performance is the main concern.
• Needs to be portable over different SQL implementations.
• The input list could contain an arbitrary number of entries.

I can think of a few ways to do it, thought I’d throw it out there and see what you folks think.

Answer 1

Since the list of fruits you are selecting from can be arbitrarily long, I would suggest the following:

create table FruitList (FruitName char(30)) insert into FruitList values ('apples'), ('pears'), ('oranges')  select * from FruitList left outer join AllFruits on AllFruits.fruit = FruitList.FruitName where AllFruits.fruit is null 

A left outer join should be much faster than ‘not in’ or other kinds of queries.