Question

我的表有几条记录，它们具有相同的MemberID。我想只得到一条记录。

select DISTINCT(MemberID)  from AnnualFees;

然后结果会来。但我想显示其他列数据，但是当我这样做时

select DISTINCT(MemberID),StartingDate,ExpiryDate,Amount  from AnnualFees;

还显示包含相同MemberID数据的所有详细信息。

有人可以帮助我。

Answer 1

假设你只想为每个memberid随机选择任何一行，你可以这样做：

select memberid, this, that, theother
from
(
select memberid, this, that, theother,
       row_number() over (partition by memberid order by this) rn
from   annualfees
)
where rn = 1;

如果您希望每个memberid有一个特定的行，例如使用最新StartDate的那个，然后您可以将其修改为：

select memberid, this, that, theother
from
(
select memberid, this, that, theother,
       row_number() over (partition by memberid order by StartDate desc) rn
from   annualfees
)
where rn = 1;

Answer 2

不知道这是否是您需要的，但您可能需要查看GROUP BY而不是DISTINCT ......

如果您有多个具有相同成员ID的记录，则可能需要指定exaclty如何从其他记录中识别出您想要的记录

例如，要了解每个成员的最后开始日期：

SELECT memberid, max(startingdate)
FROM annualfees
GROUP BY memberid

但如果您需要以这种方式识别一条记录，但也显示其他列，我认为you may need to do some trickery like this ......

例如使用连接子查询上述SELECT以加入您想要的其他列：

SELECT subq.memid, subq.startdate, a.expirydate, a.amount
FROM (
  SELECT memberid AS memid, max(startingdate) AS startdate
  FROM annualfees
  GROUP BY memberid ) subq
INNER JOIN annualfees a ON a.memberid = subq.memid 
               AND a.startingdate = subq.startdate

从头到尾，还显示数据表（使用“SET VERIFY ON”跟踪/抓取o / p）...

-- show all rows
select *
from annualfees
order by memberid, startingdate
MEMBERID               STARTINGDATE              EXPIRYDATE           AMOUNT               
---------------------- ------------------------- -------------------- -------------------- 
1                      02-DEC-09                 05-FEB-10            111                  
1                      25-JUN-10                 25-JUN-11            222                  
2                      25-APR-10                 25-JUN-13            333                  

3 rows selected

/
-- show one member`s data using max(startingdate) as selector.
SELECT memberid, max(startingdate)
    FROM annualfees
    GROUP BY memberid
MEMBERID               MAX(STARTINGDATE)         
---------------------- ------------------------- 
1                      25-JUN-10                 
2                      25-APR-10                 

2 rows selected

/ 
-- show above data joined with the other columns.
SELECT subq.memid, subq.startdate, a.expirydate, a.amount
    FROM (
      SELECT memberid AS memid, max(startingdate) AS startdate
      FROM annualfees
      GROUP BY memberid ) subq
    INNER JOIN annualfees a ON a.memberid = subq.memid AND a.startingdate = subq.startdate
MEMID                  STARTDATE                 EXPIRYDATE           AMOUNT               
---------------------- ------------------------- -------------------- -------------------- 
1                      25-JUN-10                 25-JUN-11            222                  
2                      25-APR-10                 25-JUN-13            333                  

2 rows selected

/

Answer 3

您需要选择具有重复MemberID的哪些行以某种方式返回。这将获得具有最大startingDate的行。

SELECT MemberID,StartingDate,ExpiryDate,Amount 
FROM AnnualFees af
WHERE NOT EXISTS (
        SELECT * from AnnualFees af2 
        WHERE af2.MemberID = af.MemberID 
        AND af2.StartingDate > af.StartingDate)

Answer 4

选择DISTINCT会员ID，开始日期，到期日，年度金额;

删除paranthesis

如何使用Distinct从表中仅选择一个唯一记录

4 个答案: