Postgresql 9.6. Check if a field is empty

Question

In Postgresql 9.6, I have a table like this:

ID  ADDRESS_1  ADDRESS_2
 1    bac1       def2
 2    bac2  

If I execute this

SELECT exists (SELECT ADDRESS_2 FROM my_table WHERE ADDRESS_1='bac3');

I get False answer (expected)

However, if I execute this

SELECT exists (SELECT ADDRESS_2 FROM my_table WHERE ADDRESS_1='bac2');

I get True answer (Not expected)

I reckon it is because there is a Null value.

So my objective is to obtain False value for the last one.

Any ideas or thoughts?

Thank you in advance

Answer 1

The reason the second query is "failing" is because there is a record matching the condition in the EXISTS clause. If you add logic to also insist on a non NULL value in the ADDRESS_2 column, you should get the behavior you want:

SELECT EXISTS
    (SELECT ADDRESS_2 FROM my_table
     WHERE ADDRESS_1 = 'bac2' AND ADDRESS_2 IS NOT NULL);