根据另一列获取最新日期

Question

我有一个数据集，其中包括DATETIME列和BANKCASENUMBER列。我想为每个BANKCASENUMBER选择具有最新日期的行。

这是我尝试过的：

PROC SQL;    
CREATE TABLE WORK.QUERY_FOR_WORK_QUERY_FOR_ACCOUNT AS 
   ORDER BY t1.DATETIME LIMIT 1
   SELECT t1.LOGINNAME, 
      t1.FORENAME, 
      t1.SURNAME, 
      t1.BANKCASENUMBER, 
      MAX(t1.DATETIME), 
      t1.'Inbound/outbound'n, 
      t1.'succesvol?'n
  FROM WORK.WORK_QUERY_FOR_ACCOUNTACTIVITIES t1
  GROUP BY t1.BANKCASENUMBER;
QUIT;

对于每个BANKCASENUMBER，返回的表应将包含latset DATETIME的行显示为空白。因此，每个BANKCASENUMBER应该出现一次。

Answer 1

我相信这就是您要寻找的。想法是在子查询中获取每个银行案例编号的最新时间戳，并将其加入到主表中。

PROC SQL;    
CREATE TABLE WORK.QUERY_FOR_WORK_QUERY_FOR_ACCOUNT AS
    SELECT t1.LOGINNAME, 
      t1.FORENAME, 
      t1.SURNAME, 
      t1.BANKCASENUMBER, 
      t1.DATETIME, 
      t1.'Inbound/outbound'n, 
      t1.'succesvol?'n
    FROM WORK.WORK_QUERY_FOR_ACCOUNTACTIVITIES t1
    JOIN (
        SELECT  t2.bankCaseNumber,
                MAX(t2.dateTime) as maxDateTime
        FROM WORK.WORK_QUERY_FOR_ACCOUNTACTIVITIES t2
        GROUP BY t2.BANKCASENUMBER
    ) m
        ON  m.bankCaseNumber = t1.bankCaseNumber
        AND t1.dateTime = m.maxDateTime
;
QUIT;

Answer 2

这似乎有点简单。由于我们是按LOGINNAME分组的，having语句将引用每个组中的max（DATETIME）

proc sql noprint;
   create table QUERY_FOR_WORK_QUERY_FOR_ACCOUNT as
     select * from WORK_QUERY_FOR_ACCOUNTACTIVITIES
       group by LOGINNAME
       having DATETIME = max(DATETIME);
quit;