在数据库中查找每个重复字段的最后一条记录（Oracle查询）

Question

Hy guys. I have a query:

select *
  from stat.cause_code_descriptions 
 INNER JOIN stat.stat_dial 
    on stat.cause_code_descriptions.CODE = stat.stat_dial.cause
 where called like '%3623.1348' 
   and begdt > sysdate-500 
   and rownum <=100 
 order by begdt desc

This query returns something like that

login     code     called        begdtu(unix timestamp)

oeanwel     4   VLAN:3623.1348  1336383493
oe192034    0   VLAN:3623.1348  1336382883
oe192034    2   VLAN:3623.1348  1336382640
oe192034    45  VLAN:3623.1348  1336380257
oeanwel     4   VLAN:3623.1348  1336379883
oe220850    20  VLAN:3623.1348  1336378666
oe194752    4   VLAN:3623.1348  1336378507
oeanna2510  45  VLAN:3623.1348  1336377516
oeanwel     4   VLAN:3623.1348  1336376273
oe237185    45  VLAN:3623.1348  1336374506
oe237185    4   VLAN:3623.1348  1336372662
oe237185    3   VLAN:3623.1348  1336370819
oe239364    3   VLAN:3623.1348  1336367329
oeanna2510  45  VLAN:3623.1348  1336366115

What I'm looking for is to return last(freshest) record of any login . For not repeated records my query works well, but for oe192034 and oe237185 logins it shows all records. I tried group by and distinct but it doesn't work. Please help

Answer 1

You need a window function, ROW_NUMBER:

select * 
from 
 (
   select ccd.*, sd.*, row_number() over (partition by login order by begdtu desc) rn
   from stat.cause_code_descriptions ccd
   INNER JOIN stat.stat_dial sd
      on ccd.CODE = sd.cause
   where called like '%3623.1348' 
 ) dt
where rn = 1 
order by begdt desc

Answer 2

SELECT *
FROM (
select *,ROW_NUMBER() OVER (PARTITION BY login ORDER BY begdt DESC) RN
from stat.cause_code_descriptions 
INNER JOIN stat.stat_dial on stat.cause_code_descriptions.CODE = stat.stat_dial.cause 
where called like '%3623.1348' and begdt > sysdate-500 and rownum <=100 )
WHERE RN=1;

Answer 3

Try this:

SELECT
      LOGIN,
      CODE,
      CALLED,
      BEGDTU
FROM
      (SELECT
            LOGIN,
            CODE,
            CALLED,
            BEGDTU,
            FIRST_VALUE ( LOGIN )
                OVER (PARTITION BY CODE, CALLED ORDER BY BEGDTU DESC)
                AS FIRST_ROW_ID
       FROM
                STAT.CAUSE_CODE_DESCRIPTIONS
            INNER JOIN
                STAT.STAT_DIAL
            ON STAT.CAUSE_CODE_DESCRIPTIONS.CODE = STAT.STAT_DIAL.CAUSE
       WHERE
            CALLED LIKE '%3623.1348'
            AND FIRST_ROW_ID = 1)
WHERE
      BEGDT > SYSDATE
            - 500
      AND ROWNUM <= 100
ORDER BY
      BEGDT DESC