如何获取结果集的交集？

Question

结果集1：

select code from quote where cond1

结果集2：

select code from vix  where cond2

我想要一个包含 code 的集合，它是 Result set1 和 Result set2 的交集。

select code from quote where cond1 and code in (select code from vix  where cond2);

无法正常工作！GMB 和 Akina 的回答的错误信息相同。

RROR 1267 (HY000)：非法混合排序规则 (utf8mb4_general_ci,IMPLICIT) 和 (utf8mb4_unicode_ci,IMPLICIT) 用于操作 '='

让我们显示 table 结构：

show create table quote;
+-------+------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                                                                                                                                                                                                                                                                             |
+-------+-----------------------------------------------------------------
| quote | CREATE TABLE `quote` (
  `id` int(8) unsigned NOT NULL AUTO_INCREMENT,
  `code` text COLLATE utf8mb4_unicode_ci,
  `date` date DEFAULT NULL,
  `open` double DEFAULT NULL,
  `high` double DEFAULT NULL,
  `low` double DEFAULT NULL,
  `close` double DEFAULT NULL,
  `volume` bigint(20) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=17173979 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci |
+-------+--------------------------------------------------------------------+

show create table vix;
+-------+-------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                                  |
+-------+--------------------------------------------------------------------+
| vix   | CREATE TABLE `vix` (
  `code` text,
  `span` smallint(6) DEFAULT NULL,
  `vix` double DEFAULT NULL,
  `extrem_date` date DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 |

从 table quote 和 vix.

中搜索代码集

select code from quote where volume > 10000000 and date='2020-08-24';
+-------+
| code  |
+-------+
| zom   |
| ibio  |

注意：大约 120 行。

select code from vix  where span >30;
+---------+
| code    |
+---------+
| canf    |
| ensv    |

注意：大约 1100 行。获取两个结果集的交集：

MariaDB [stock]> select code 
    -> from quote q 
    -> where 
    ->     volume > 10000000 and date='2020-08-24'
    ->     and exists (select 1 from vix v where span >30 and (v.code = q.code));
ERROR 1267 (HY000): Illegal mix of collations (utf8mb4_general_ci,IMPLICIT) and (utf8mb4_unicode_ci,IMPLICIT) for operation '='

Answer 1

您的（伪）查询查询应该可以满足您的要求。但是，我发现当值列表变大时，使用 exists 会更有效。我会这样表述：

select code 
from quote q 
where 
    cond1
    and exists (select 1 from vix v where cond2 and v.code = q.code)

Answer 2

SELECT code 
FROM (select code from quote where cond1) q1
JOIN (select code from vix   where cond2) q2 USING (code)

Answer 3

select code 
from quote q 
where 
    cond1
    and exists (select 1 from vix v where cond2 and (v.code collate utf8mb4_unicode_ci = q.code))

如何获取结果集的交集？

How to get the result set's intersection?

mysql

sql

subquery