如何获取 4 个不同值的 ID(2 个键的组合)

How to get Ids of 4 distinct values ( combination of 2 keys )(如何获取 4 个不同值的 ID(2 个键的组合))

问题描述

我得到了如下表

mysql> select * from tb_dts;
+----+------+------+
| Id | key1 | key2 |
+----+------+------+
|  1 |    1 |    1 |
|  2 |    1 |    1 |
|  3 |    1 |    1 |
|  4 |    2 |    1 |
|  5 |    2 |    1 |
|  6 |    2 |    1 |
|  7 |    2 |    1 |
|  8 |    1 |    2 |
|  9 |    1 |    2 |
| 10 |    1 |    2 |
| 11 |    1 |    2 |
| 12 |    1 |    2 |
| 13 |    3 |    1 |
| 14 |    3 |    1 |
| 15 |    3 |    1 |
| 16 |    3 |    1 |
| 17 |    2 |    2 |
| 18 |    2 |    2 |
| 19 |    2 |    2 |
| 20 |    2 |    3 |
| 21 |    2 |    3 |
| 22 |    2 |    3 |
| 23 |    3 |    2 |
| 24 |    3 |    2 |
| 25 |    3 |    2 |
| 26 |    3 |    2 |
+----+------+------+
26 rows in set (0.00 sec)

我采用这样的不同值，用于某些应用程序分页

I take distinct values like this, used in some application pagination

mysql> select distinct key1,key2 from tb_dts limit 0,4;
+------+------+
| key1 | key2 |
+------+------+
|    1 |    1 |
|    1 |    2 |
|    2 |    1 |
|    2 |    2 |
+------+------+
4 rows in set (0.00 sec)

mysql> select distinct key1,key2 from tb_dts limit 4,4;
+------+------+
| key1 | key2 |
+------+------+
|    2 |    3 |
|    3 |    1 |
|    3 |    2 |
+------+------+
3 rows in set (0.00 sec)

通过 group_concat 我也得到了 ID，但是我想在 WHERE Field IN 子句中使用这个 ID，例如 where somefield IN ( ..here my Ids去...)

Through group_concat I get Ids as well but, I want to use this Ids in WHERE Field IN clause like where somefield IN ( ..here my Ids goes...)

mysql> select key1,key2,group_concat(Id) from tb_dts group by key1,key2 limit 0,4;
+------+------+------------------+
| key1 | key2 | group_concat(Id) |
+------+------+------------------+
|    1 |    1 | 1,2,3            |
|    1 |    2 | 8,9,10,11,12     |
|    2 |    1 | 4,5,6,7          |
|    2 |    2 | 17,18,19         |
+------+------+------------------+
4 rows in set (0.00 sec)

mysql> select key1,key2,group_concat(Id) from tb_dts group by key1,key2 limit 4,4;
+------+------+------------------+
| key1 | key2 | group_concat(Id) |
+------+------+------------------+
|    2 |    3 | 20,21,22         |
|    3 |    1 | 13,14,15,16      |
|    3 |    2 | 23,24,25,26      |
+------+------+------------------+
3 rows in set (0.00 sec)

但是我如何把它放在 WHERE Fieldname IN 子句中?

But How do I put this in WHERE Fieldname IN clause ?

我需要这样的东西，因为我的 tb_dts 包含超过 3000 万 个记录，而 15 个实际字段，我不能使用 ID BETWEEN min_id 和 max_id

I need something like this, as my tb_dts contains more that 30 million reocrds, and 15 fields in real, I can't use ID BETWEEN min_id and max_id

用于处理我需要的前 4 个唯一组合值

For processing first 4 unique combination values I need

select * from tb_dts where Id IN (1,2,3,8,9,10,11,12,4,5,6,7,17,18,19  )

为了处理接下来的 4 个唯一组合值，我需要在我的应用程序中使用 Id，所以简而言之，我希望在我的 where Field IN 子句中使用下面提到的 Id

For processing next 4 unique combination values I need Ids in my application, so in short I want to have below mentioned Ids in my where Field IN clause

select * from tb_dts where Id IN (20,21,22,13,14,15,16,23,24,25,26 )

这是我的表格结构

DROP TABLE IF EXISTS `tb_dts`;
CREATE TABLE `tb_dts` (
  `Id` int(11) NOT NULL AUTO_INCREMENT,
  `key1` int(11) DEFAULT '-99',
  `key2` int(11) DEFAULT '-99',
  PRIMARY KEY (`Id`),
  KEY `main` (`key1`,`key2`)
) ENGINE=MyISAM AUTO_INCREMENT=27 DEFAULT CHARSET=latin1;

LOCK TABLES `tb_dts` WRITE;
INSERT INTO `tb_dts` VALUES (1,1,1),(2,1,1),(3,1,1),(4,2,1),(5,2,1),(6,2,1),(7,2,1),(8,1,2),(9,1,2),(10,1,2),(11,1,2),(12,1,2),(13,3,1),(14,3,1),(15,3,1),(16,3,1),(17,2,2),(18,2,2),(19,2,2),(20,2,3),(21,2,3),(22,2,3),(23,3,2),(24,3,2),(25,3,2),(26,3,2);
UNLOCK TABLES;

正如您在此处看到的，它为每个不同的组合值提供了第一个找到的 Id

mysql> select Id from tb_dts group by key1,key2 limit 0,4;
+----+
| Id |
+----+
|  1 |
|  8 |
|  4 |
| 17 |
+----+
4 rows in set (0.00 sec)

但我希望所有 Ids 都符合给定的标准，这只不过是所有 ID 都低于 4 个唯一值

But I expect all Ids which falls within the criteria given, that is nothing but what all IDs falls for below 4 unique value

mysql> select key1,key2 from tb_dts group by key1,key2 limit 0,4;
+------+------+
| key1 | key2 |
+------+------+
|    1 |    1 |  --- 1,2,3
|    1 |    2 |  --- 8,9,10,11,12
|    2 |    1 |  --- 4,5,6,7 
|    2 |    2 |  --- 17,18,19
+------+------+
4 rows in set (0.00 sec)

预期 o/p

我希望为 group by key1,key2 limit 0,4 获得这样的 Id，以便可以在我的 WHERE IN子句.

1
2
3
8
9
10
11
12
4
5
6
7
17
18
19

select t.*
from your_table t
where exists (
    select 1 from (
        select group_concat(Id)
        from tb_dts
        group by key1, key2
        order by key1, key2   -- very important when using limit
        limit 0, 4
    ) t2 where find_in_set(t.fieldname, t2.ids) > 0
);

create index idx_tb_dts on tb_dts (key1, key2, id);

select t.*
from your_table t
where exists (
    select 1
    from tb_dts t1
    inner join (
        select distinct key1, key2
        from tb_dts
        order by key1, key2
        limit 0, 4
    ) t2 on t1.key1 = t2.key1
    and t1.key2 = t2.key2
    where t1.id = t.fieldname
);

create table the_keys_table(
    key1 int not null,
    key2 int not null,
    primary key (key1, key2)
);

select key1, key2       -- no distinct or group by needed.
from the_keys_table
order by key1, key2
limit 0, 4

select t.*
from your_table t
where exists (
    select 1
    from tb_dts t2
    where (key1, key2) in (
        select key1, key2
        from the_keys_table
        order by key1, key2
        limit 0, 4
    ) and t1.id = t.fieldname
);