postgresql return true if table relationship

Question

I have a query for a table, garage. Garages have cars linked to them through column (garage_id).

I want a postgresql query that will return all the garages, but also will return true in a seperate column if it has at least one car assigned to it.

For example:

Garage A name, no cars
Garage B name, 2 cars
Garage C name, 1 car
Garage D name, no cars

Should return:

Garage A name, false
Garage B name, true
Garage C name, true
Garage D name, false

Clodoaldo Neto · Accepted Answer · 2014-08-23 11:33:17Z

1

select g.name, bool_or(c.garage_id is not null)
from
    garage g
    left join
    car c on g.garage_id = c.garage_id
group by g.name

answered Aug 23, 2014 at 11:33

Clodoaldo Neto

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