加入所有值都存在的表的 SQL 有效方法 [英] SQL efficient way to join a table where all values exist

问题描述

table 1
item    group_id
123     aaaa
432     bbbb
534     aaaa
765     cccc
656     aaaa
656     cccc
111     cccc

group_id    group_name
aaaa        groupA
bbbb        groupB
cccc        groupC

我想找到同时包含 765 和 656 的所有组 - 在本例中 GroupC 包含这两个值.

I want to find all groups that contain both 765 and 656 - in this instance GroupC contains both of those values.

有没有办法避免一堆嵌套查询或 AND 语句?假设表 1 可以有数千个配对，我必须找到包含 30 个项目的所有列表的组编写一个非常大的查询来回答问题会很丑陋.

Is there a way that avoids a bunch of nested queries or AND statements? Say if table 1 can have thousands of pairings and I have to find the groups that contain all of a list of 30 items It would be ugly to write a really big query to answer the question.

我希望我可以说在 (765,656) 中的位置"，但让它的行为有所不同.如果有一堆要匹配的项目，它会变得混乱.

I wish I could say "where in (765,656)" but have it behave differently. If there was a bunch of items to match on it would get messy.

SQL Fiddle http://sqlfiddle.com/#!9/6581eb/9

SQL Fiddle http://sqlfiddle.com/#!9/6581eb/9

示例数据(以防 SQL Fiddle 由于某种原因无法访问):

Sample data (in case SQL Fiddle is inaccessible for some reason):

create table table1(itemID int,groupID varchar(4));
insert into table1(itemID,groupID)
values
  (123,'aaaa')
  ,(432,'bbbb')
  ,(534,'aaaa')
  ,(765,'cccc')
  ,(656,'aaaa')
  ,(656,'cccc')
  ,(111,'cccc');

create table table2(groupID varchar(4),groupName varchar(6));
insert into table2(groupID,groupName)
values
  ('aaaa','groupA')
  ,('bbbb','groupB')
  ,('cccc','groupC');

推荐答案

最简单的方法是使用 group by 和 have :

The simplest thing would be to use group by and having:

SELECT group_name
FROM table2 g
JOIN table1 t on g.group_id = t.group_id
WHERE t.item in (765,656)
GROUP BY group_name
HAVING COUNT(DISTINCT t.item) = 2

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