In SQL, how to assign the value of a column to null without using the CASE statement, using the nested NULLIF function when condition A or condition B is met

Question

I have a column C1 whose value can be 'values', 'empty' or 'N/A'.

| C1 |
-------
| |
| N/A |
|apple|

I want to select column C1 in a way that converts null values ​​and N/A to NULL, using NULLIF.

| C1 |
-------
|NULL |
|NULL |
|apple|

We can use NULLIF(C1, ''), which returns NULL if the column value is empty.

We can also use CASE to achieve these two situations, but I want to know if there is a way to use NULLIF to achieve it, and if so, how to achieve it? (Or other methods besides CASE)

Similar to NULLIF(C1, '' OR 'N/A')

Thanks in advance.

Answer 1

Use caseExpression:

(case when c1 not in ('', 'N/A') then c1 end)

Answer 2

You can use nested NULLIF() functions to achieve:

NULLIF(NULLIF(c1, ''), 'N/A')

See Demo.