Question 2 Recall the Beers database and some (approximate) table definitions from that database: create table Beers (name text primary key, brewer text); create table Drinkers (name text primary key, address text, phone text );
Question 2 Recall the Beers database and some (approximate) table definitions from that database: create table Beers (name text primary key, brewer text); create table Drinkers (name text primary key, address text, phone text );
Computer Networking: A Top-Down Approach (7th Edition)
7th Edition
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Question
Transcribed Image Text:Question 2,
Recall the Beers database and some (approximate) table definitions from that database:
create table Beers (name text primary key, brewer text );
create table Drinkers (name text primary key, address text, phone text);
create table Likes (drinker text references Drinkers (name),
Which of the following queries (maybe more than one) answers the question "Which drinkers like every beer?"
Note that there may be no drinkers that satisfy this property in the original instance of the database.
(a) O
(b) O
(d) O
(e) O
select d.name
from
where
beer text references Beers (name),
primary key (drinker, beer) );
Drinkers d
not exists (
(select L.beer as name from Likes L where L.drinker = d.name)
);
select d.name
from Drinkers d
where
);
except
(select name from Beers)
not exists (
(select name from Beers)
except
(select L.beer as name from Likes L where L.drinker = d.name)
select d.name
from
Drinkers d
where (select count(*) from Beers)
(select count (L.beer) from Likes L where L.drinker = d.name);
);
select d.name
from Drinkers d
where
exists (
(select L.beer as name from Likes L where L.drinker = d.name)
except
(select name from Beers)
None of above options is correct
Transcribed Image Text:Question 1
Consider the following table definitions:
create table x ( id integer primary key, name text unique );
create table y (id integer primary key, x_id integer references x(id), defn text );
Which of the following SQL queries will return a list of names of x's and a count of the number of y tuples each is associated with?
There may be more than one correct answer.
(a) O
(b) 0
(c)
(d) O
(e) O
(f) O
select x.name, count (y.id)
from x join y on (x.id = y.x_id)
group by x. name;
select x.name, count (y.id)
from x left outer join y on (x.id = y.x_id)
group by x.name;
select x.name, count (y.id)
from x right outer join y on (x.id = y.x_id)
group
by x. name;
select x.name,
(select count(x_id) from y where y.x_id = x.id) as count
from x full outer join y on (x.id = y.x_id);
select distinct x.name,
from
(select count (x_id) from y where y.x_id = x.id) as count
x full outer join y on (x.id = y.x_id);
None of the above is correct
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