Comprison on NULL differes from SQL

Hi,

We have noticed that the result of the following example doesn’t return the expected result (based on https://doi.org/10.14778/3151113.3151116)

alasql('CREATE TABLE R (a number)');
alasql('CREATE TABLE S (b number)');
alasql.tables.R.data = [ {a: 1}, {a: null} ];
alasql.tables.S.data = [ {b: null} ];
var res = alasql('select a from R where a not in (select b from S)');
// expected: res = []
// alasql:   res = [ {"a": 1} ]

See https://jsfiddle.net/3ya794kr/.

This query compares each row of R with NULL which always returns unknown in SQL. Since not in unknown is unknown, the result should be the empty collection.

[piotr-m-bielski]

I tried to do that, but It is really hard to understand how it works. (parser) Variables like yy do not help. I will try again over this weekend

[mathiasrw]

Oh - we can work on a solution. So you can just start on this. But before the release we will discuss how to let the users configure this. How we do that depends on what the solution looks like. So I suggest you work on solving this, and then we talk about how the solution can be part of what Alasql offers.