Adding a conditioned extra field to a query result

I have these two tables

TABLE 1 ( tournaments_data )

tournament_id | accound_id | data1 | data2

TABLE 2 ( tournaments_subscriptions )

tournament_id | account_id

Here, i have to read data of table 1 like this

SELECT data1,data2 from tournaments_data WHERE 1

adding an extra field to each row result, which has to be true if a specific account_id is subscribed to a specific tournament, and has to be false if the account_id is not subscribed. A account_id is subscribed to a tournament if we can find a row in the second table where accound_id is coupled to a specific tournament_id. A practical example

tournament_id | account_id | data1 | data2
      1             1        data1a  data2a
      2             5        data1b  data2b

tournament_id | account_id
      1             1

Expected result

data1a data2a true
data1b data2b false

querying for account_id=1. Hope it’s clear enough.

Answer

I assumed both columns are named account_id and there was a typo.

You can use a LEFT JOIN. For example:

select
  d.data1,
  d.data2,
  case when s.tournament_id is null then 'false' else 'true' end
from tournaments_data d
left join tournaments_subscriptions s
   on s.tournament_id = d.tournament_id
  and s.account_id = d.account_id
  and s.account_id = 1 -- specific account

Result:

data1   data2   case w...
------  ------  ---------
data1a  data2a  true
data1b  data2b  false

See running example at DB Fiddle.