MySQL需要返回组内结果集中的特定记录

Question

我需要构建一个MySQL查询，我可以根据一个或多个列值对结果进行分组，然后返回该组中匹配某些条件的完整记录。

采取如下图所示为代表我的数据表：

| ID | NAME | Editor | Modified date | Type | 
| 1 | doc1 | Smith | 2012-01-01 | A | 
| 2 | doc2 | Smith | 2012-03-03 | A | 
| 3 | doc1 | Jones | 2012-10-10 | A | 
| 4 | doc1 | Scott | 2011-01-01 | A | 
| 5 | doc2 | Boyd | 2013-01-01 | A | 
| 6 | doc3 | Smith | 2010-01-01 | B | 
| 7 | doc4 | Smith | 2010-03-03 | B | 
| 8 | doc3 | Jones | 2010-10-10 | B | 
| 9 | doc3 | Scott | 2009-01-01 | B | 
| 10 | doc4 | Boyd | 2011-01-01 | B | 

我要回有关的任何文件，即最近修改的记录。

| ID | NAME | Editor | Modified date | Type | 
| 3 | doc1 | Jones | 2012-10-10 | A | 
| 5 | doc2 | Boyd | 2013-01-01 | A | 
| 8 | doc3 | Jones | 2010-10-10 | B | 
| 10 | doc4 | Boyd | 2011-01-01 | B | 

或与之相关的A型

| ID | NAME | Editor | Modified date | Type | 
| 3 | doc1 | Jones | 2012-10-10 | A | 
| 5 | doc2 | Boyd | 2013-01-01 | A | 

我试图GROUP BY和HAVING而据我所知，他们将不会返回整个记录的moste最近修改的记录。

附录：这可能是我需要阿尔特的“最近”预选赛“之前给定的日期”

Answer 1

使用子查询：

SELECT tbl.* FROM tbl 
INNER JOIN (
    SELECT max(Modifed_date) as newestRecordDate, Editor 
    FROM tbl 
    GROUP BY Editor 
) as Newest 
on tbl.Modifed_Date = Newest.NewestRecordDate 

按类型：

SELECT * FROM tbl 
INNER JOIN (
    SELECT max(Modifed_date) as newestRecordDate, Editor 
    FROM tbl 
    GROUP BY Editor 
) as Newest 
ON tbl.Modifed_Date = Newest.NewestRecordDate 
WHERE Type = 'A' 

注意，修改日期不包括时间的可能的问题为好，并具有更每天编辑一次 - 确保此记录也包含时间部分。

Answer 2

如果要返回最近修改的行，那么你可以使用：

select * 
from yourtable t1 
where `Modified date` = (select max(`Modified date`) 
         from yourtable t2 
         where t1.NAME = t2.NAME 
         group by `NAME`); 

见SQL Fiddle with Demo

然后，如果您希望只返回那些type='A'，那么下面的工作：

select * 
from yourtable t1 
where `Modified date` = (select max(`Modified date`) 
         from yourtable t2 
         where t1.NAME = t2.NAME 
         group by `NAME`) 
    and type = 'A'; 

见SQL Fiddle with Demo

Answer 3

试试这个：

对于第一个问题：

SELECT a.ID, a.name, a.Editor, a.ModifiedDate, a.Type 
FROM tableName a 
INNER JOIN (SELECT b.name, MAX(b.ModifiedDate) ModifiedDate 
      FROM tableName b GROUP BY b.name 
      ) b ON a.name = b.name AND a.ModifiedDate = b.ModifiedDate 

输出

| ID | NAME | EDITOR |     MODIFIEDDATE | TYPE | 
-------------------------------------------------------------- 
| 3 | doc1 | Jones | October, 10 2012 00:00:00+0000 | A | 
| 5 | doc2 | Boyd | January, 01 2013 00:00:00+0000 | A | 
| 8 | doc3 | Jones | October, 10 2010 00:00:00+0000 | B | 
| 10 | doc4 | Boyd | January, 01 2011 00:00:00+0000 | B | 

并滤波Type='A'：

SELECT a.ID, a.name, a.Editor, a.ModifiedDate, a.Type 
FROM tableName a 
INNER JOIN (SELECT b.name, MAX(b.ModifiedDate) ModifiedDate 
      FROM tableName b GROUP BY b.name 
      ) b ON a.name = b.name AND a.ModifiedDate = b.ModifiedDate 
WHERE a.Type = 'A' 

输出

| ID | NAME | EDITOR |     MODIFIEDDATE | TYPE | 
-------------------------------------------------------------- 
| 3 | doc1 | Jones | October, 10 2012 00:00:00+0000 | A | 
| 5 | doc2 | Boyd | January, 01 2013 00:00:00+0000 | A | 

入住这SQL FIDDLE DEMO

Answer 4

select * from your_table group by NAME order by Modified_Date DESC; 
select * from your_table where Type = 'A' group by NAME order by Modified_Date DESC;