PostgreSQL represent varchar column as boolean

Question

I have the following query:

SELECT id, first_name from users;

I want to represent first_name column as a boolean. If user have first_name it will be true, if not it will be false. How can I do that in PostgreSQL?

user330315 · Accepted Answer · 2017-09-01 11:23:20Z

3

Just test for not null:

SELECT id, first_name is not null  as has_first_name
from users;

If you want to consider an empty string ('') as "no first name as well, you can use:

SELECT id, nullif(first_name,'') is not null  as has_first_name
from users;

answered Sep 1, 2017 at 11:23

user330315

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Comments

Radim Bača · Accepted Answer · 2017-09-01 11:22:53Z

1

SELECT id, 
       CASE WHEN first_name IS NULL THEN 'false' ELSE 'true' END
FROM users;

answered Sep 1, 2017 at 11:22

Radim Bača

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2 Comments

user330315 Over a year ago

Nitpick: 'false' is not a boolean, it's a character value

Radim Bača Over a year ago

@a_horse_with_no_name you are right, that is 'true'. on the other hand, these values are implicitly converted to boolean if need.

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