Question

我有这样的数据。

REPORTER    SUMMARY                CREATED          UPDATED status  servicetype  
e159299 Route card from August  7/29/2013   22:46.0    5    New Route Card
e159299 I have returned the     6/11/2013   32:09.7    5    Cancel Route Card
e159324 New Route Card: RBI     1/2/2013    00:51.0    5    New Route Card
e159324 Hi, I would require     10/30/2013  35:23.0    5    New Route Card
e159299 Cancel Route Card       4/30/2013   53:26.2    5    Cancel Route Card

我需要获得特定记者的最新记录条目。即我需要为记者做分组，并需要获得组合创建字段的最新记录。

我的输出必须是这样的。

 e159299    Route card from August  7/29/2013   22:46.0    5    New Route Card  
 e159324    Hi, I would require     10/30/2013  35:23.0    5    New Route Card

Answer 1

分析函数非常适合此类查询：

select *
from (
   select reporter
   ,      summary
   ,      created
   ,      updated_status
   ,      servicetype
   ,      max(created) over (partition by reporter) last_created
   from   yout_table t)
where created = last_created;

Answer 2

分析函数是为此设计的 - 只需GROUP BY相应的列（在本例中为REPORTER），并在每个其他行上使用MAX( <column_name> ) KEEP ( DENSE_RANK LAST ORDER BY <ordering_column> )。

SQL Fiddle

Oracle 11g R2架构设置：

CREATE TABLE tbl ( REPORTER, SUMMARY, CREATED, UPDATED, status, servicetype ) AS
          SELECT 'e159299', 'Route card from August', '7/29/2013',  '22:46.0', 5, 'New Route Card' FROM DUAL
UNION ALL SELECT 'e159299', 'I have returned the',    '6/11/2013',  '32:09.7', 5, 'Cancel Route Card' FROM DUAL
UNION ALL SELECT 'e159324', 'New Route Card: RBI',    '1/2/2013',   '00:51.0', 5, 'New Route Card' FROM DUAL
UNION ALL SELECT 'e159324', 'Hi, I would require',    '10/30/2013', '35:23.0', 5, 'New Route Card' FROM DUAL
UNION ALL SELECT 'e159299', 'Cancel Route Card',      '4/30/2013',  '53:26.2', 5, 'Cancel Route Card' FROM DUAL;

查询1 ：

SELECT REPORTER,
       MAX( SUMMARY     ) KEEP ( DENSE_RANK LAST ORDER BY TO_DATE( CREATED, 'MM/DD/YYYY' ) ) AS SUMMARY,
       MAX( CREATED     ) KEEP ( DENSE_RANK LAST ORDER BY TO_DATE( CREATED, 'MM/DD/YYYY' ) ) AS CREATED,
       MAX( UPDATED     ) KEEP ( DENSE_RANK LAST ORDER BY TO_DATE( CREATED, 'MM/DD/YYYY' ) ) AS UPDATED,
       MAX( status      ) KEEP ( DENSE_RANK LAST ORDER BY TO_DATE( CREATED, 'MM/DD/YYYY' ) ) AS status,
       MAX( servicetype ) KEEP ( DENSE_RANK LAST ORDER BY TO_DATE( CREATED, 'MM/DD/YYYY' ) ) AS servicetype
FROM tbl
GROUP BY REPORTER

<强> Results ：

| REPORTER |                SUMMARY |    CREATED | UPDATED | STATUS |    SERVICETYPE |
|----------|------------------------|------------|---------|--------|----------------|
|  e159299 | Route card from August |  7/29/2013 | 22:46.0 |      5 | New Route Card |
|  e159324 |    Hi, I would require | 10/30/2013 | 35:23.0 |      5 | New Route Card |

Answer 3

试试这个......

SELECT * FROM table ORDER BY CREATED DESC LIMIT 0,2

此查询适用于mysql数据库

查找最新记录条目

3 个答案: