Re: Update column2 on all lines automatically to Y, when column1 is unique and column2 is N

[Peter Brawley]

Break problems into parts. The values of col that occur just once in table t are ...

select col, count(*) as X
from t
group by col
having X=1;

... in your case ...

select enti_users, count(*) as X
from tabela_users
group by enti_users
having X=1;

So you can write something like ...

update tabela_users as a
join (
select enti_users, count(*) as X
from tabela_users
group by enti_users
having X=1
) as b using(enti_users)
set a.flgd_users = 'Y'
where a.column2='N';

... substituting the correct name for `column2`.