[FEATURE] `IS NOT NULL` condition support

[Swiddis]

Is your feature request related to a problem?

Going through a list of old error case reports for #5261, I found this one:

When running a PPL query coming from SQL, you may be tempted to try where field is not null. This is an error. Instead you should run where isnotnull(field). The error reporting task is to suggest the latter when the former is written.

What solution would you like?

Except... If we have full logic to accurately detect what was written & meant, and suggest an alternative, why not just... Implement it? This issue is about adding support for field IS [NOT] NULL as a synonym for is[not]null(field).

What alternatives have you considered?

Just continue with adding error case detection for it.

Do you have any additional context?

N/A

[ThyTran1402]

Hi @Swiddis

I think this is a nice feature to have for error handling. I can try to work on this issue. I'm thinking we can have field IS NULL/field IS NOT NULL is identical to isnull(field)/isnotnull(field.

Please let me know if that works.

Thank you!