Question

当前，我有一个下表，我想提取ID为带有Estimate_date的记录，这些记录被分配给update_index值的最小值，如果该值为空，我想去分配给下一个update_index的值，< / p>

例如，用于

记录

id = 73，我想获取值2017-06-13 00:00:00
id = 75，我想获取值2017-01-01 00:00:00
id = 76，我想获取值2018-06-01 00:00:00

输入表

+----+--------------+---------------------+
| id | update_index |    estimated_date   |
+----+--------------+---------------------+
| 73 |       1      | 2017-06-13 00:00:00 |
+----+--------------+---------------------+
| 73 |       2      | 2017-01-13 00:00:00 |
+----+--------------+---------------------+
| 73 |       3      | 2017-05-13 00:00:00 |
+----+--------------+---------------------+
| 73 |       4      |         NULL        |
+----+--------------+---------------------+
| 75 |       1      | 2017-01-01 00:00:00 |
+----+--------------+---------------------+
| 75 |       2      |         NULL        |
+----+--------------+---------------------+
| 75 |       3      | 2019-01-01 00:00:00 |
+----+--------------+---------------------+
| 76 |       1      |         NULL        |
+----+--------------+---------------------+
| 76 |       2      | 2018-06-01 00:00:00 |
+----+--------------+---------------------+

输出表

+----+--------------+---------------------+
| id | update_index |    estimated_date   |
+----+--------------+---------------------+
| 73 |       1      | 2017-06-13 00:00:00 |
+----+--------------+---------------------+
| 75 |       1      | 2017-01-01 00:00:00 |
+----+--------------+---------------------+
| 76 |       2      | 2018-06-01 00:00:00 |
+----+--------------+---------------------+

我尝试了以下值，但我始终只能获得一条记录，您能帮我吗？

SELECT  id,update_index,estimated_date
FROM tablename where estimated_date = (
       SELECT DISTINCT estimated_date
       FROM tablename
        where estimated_date is not null
       ORDER BY id, udpate_index ASC
       LIMIT 1);
 `

Answer 1

我将使用相关的子查询：

select t.*
from tablename t
where t.update_index = (select t2.update_index
                        from tablename t2
                        where t2.id = t.id and t2.estimated_date is not null
                        order by t2.update_index asc
                        limit 1
                       );

Answer 2

请尝试这个。

    select t2.*
    from
    (select id, min(update_index) updated_index 
    from input_table 
    where estimated_date is not null
    group by 1 )t1
    left join input_table t2
    on t1.id = t2.id
    and t1.update_index = t2.update_index

Answer 3

您无法尝试：

选择t.id，t.update_index，t.estimated_date 来自表名t 其中t.update_index =（从表名t1中选择MIN（update_index），其中t1.id = t.id和t1.estimated_date不为null）按t.id分组

Answer 4

在LIMIT子句中使用子查询：

select t.*
from table t
where t.update_index = (select t2.update_index
                        from table t2
                        where t2.id = t.id and t2.estimated_date is not null
                        order by t2.estimated_date desc
                        limit 1
                       );

但是，您的示例数据更能提示我：

select t.*
from table t
where t.estimated_date = (select max(t2.estimated_date)
                          from table t2
                          where t2.id = t.id and t2.estimated_date is not null
                         );

如果您与estimated_date有联系，则可以采用第一种方法。

选择与LIMIT条件不同的MYSQL查询

4 个答案: