SQL select a parent with children only in - sql

Question

if you have parent table
create table parent (
pid int not null,
name varchar(255)
)
and a parent-child join table
create table parent_child (
pid int not null,
cid int not null,
foreign key (pid) references parent(pid),
foreign key (cid) references child(cid)
)
create table child(
cid int not null,
name varchar(255)
)
How can I find all parent's names where all their children have names in the following list ('dave','henry','myriam','jill').
I don't want to see a parent if they have a child with a different name, but if they have 1 or more children and all their children have names in the list I want to see the parent's name.
I did find this https://stackoverflow.com/a/304314/1916621 that will help me find a parent with children of the exactly those names, but I can't figure out how to the parents who only have children with names in a subset of that list.
Extra points if someone knows performance tradeoff for different approaches.

Answer 1

SELECT
p.pid,
p.name
FROM
parent p
WHERE NOT EXISTS (
SELECT *
FROM
parent_child pc
JOIN child c
ON pc.cid = c.cid
AND c.name NOT IN ('dave','henry','myriam','jill')
WHERE
p.pid = pc.pid
) AND EXISTS (
SELECT *
FROM
parent_child pc
JOIN child c
ON pc.cid = c.cid
AND c.name IN ('dave','henry','myriam','jill')
WHERE
p.pid = pc.pid
)
Another method... no sub-queries, but additional DISTINCT needed to eliminate duplication of parent records from joining to the parent_child table.
SELECT DISTINCT
p.pid,
p.name
FROM
parent p
JOIN parent_child pc_exists ON pc_exists.pid = p.pid
JOIN child c_exists
ON c_exists.cid = pc_exists.cid
AND c_exists.name IN ('dave','henry','myriam','jill')
LEFT JOIN parent_child pc_notExists ON pc_notExists.pid = p.pid
LEFT JOIN child c_notExists
ON c_notExists.cid = pc_notExists.cid
AND c_notExists.name NOT IN ('dave','henry','myriam','jill')
WHERE
c_notExists.cid IS NULL

Answer 2

Here is my moderate bet:
Sample tables:
Parent
PID NAME
1 dad john
2 mum sandy
3 dad frank
4 mum kate
5 mum jean
Child
CID NAME
11 dave
22 maryam
33 henry
44 maryam
16 jill
17 lina
23 jack
34 jill
55 dave
Parent_Child
PID CID
1 11
1 16
1 17
2 22
3 33
4 44
2 23
5 55
3 34
Query:
select p.pid, p.name,
group_concat(c.name) as children
from parent as p
inner join parent_child as pc
on p.pid = pc.pid
join child as c
on pc.cid = c.cid
where c.name
in ('dave','henry','maryam','jill')
group by p.pid
;
Results:
PID NAME CHILDREN
1 dad john dave,jill
2 mum sandy maryam
3 dad frank henry,jill
4 mum kate maryam
5 mum jean dave
SQLFIDDLE
Using REGEXP and GROUP_CONCAT
It is something much better than in or find_in_set for SQL. The change I did, I used the list as a comma delimitted string ;)
*But the issue here: that group_concat string order has to be found in the comman delimitted string.* Unless we make the REGEXP much efficient :)
Query:
select x.pid, x.name,
x.children from(
select p.pid, p.name,
group_concat(c.name) as children,
count(c.name) as counts
from parent as p
inner join parent_child as pc
on p.pid = pc.pid
join child as c
on pc.cid = c.cid
group by p.pid) as x
where 'dave,maryam,henry,jill'
REGEXP x.children
;
Results:
PID NAME CHILDREN
3 dad frank henry,jill
4 mum kate maryam
5 mum jean dave
*SQLFIDDLE