SQL选择一个只有孩子的父母

Question

如果你有父表

create table parent (
  pid int not null,
  name varchar(255)
)

还有一个父子连接表

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)
)

我如何在以下列表（'dave','henry','myriam','jill'）中找到所有孩子的名字的所有父母的名字。

如果父母有一个不同名字的孩子，我不想看到他们，但是如果他们有 1 个或多个孩子并且他们的所有孩子的名字都在列表中，我想看到父母的名字。

我确实找到了这个https://*.com/a/304314/1916621，这将帮助我找到一个拥有这些名字的孩子的父母，但我不知道如何找到那些只有孩子名字在该列表子集中的父母。

如果有人知道不同方法的性能权衡，则加分。

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
)

另一种方法...没有子查询，但需要额外的DISTINCT 来消除parent 记录的重复加入parent_child 表。

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

这是我的中等赌注：

示例表：

家长

PID     NAME
1       dad john
2       mum sandy
3       dad frank
4       mum kate
5       mum jean

儿童

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

查询：

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
;

结果：

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

---

使用 REGEXP 和 GROUP_CONCAT

对于 SQL，它比 in 或 find_in_set 要好得多。我所做的更改，我将列表用作comma delimitted string ;)

*但这里的问题是：group_concat 字符串顺序必须在逗号分隔的字符串中找到。* 除非我们让REGEXP 更高效:)

查询：

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
;

结果：

PID     NAME        CHILDREN
3       dad frank   henry,jill
4       mum kate    maryam
5       mum jean    dave

*SQLFIDDLE