查询帮助 - 匹配阶段并返回最近的一个

Question

下面的代码显示有多个候选人的学生，但不是他们当前的。学生不能在同一年，期限和部门不止一个候选人，所以这是针对他们，这样我可以批量删除它们。

我需要的代码，将只针对最高阶段添加。如果阶段相匹配，它会采取一个与最近的日期（hist_stage_dte）。我需要帮助。不胜感激。谢谢！

SELECT * 
FROM candidacy 
WHERE (candidacy.yr_cde = '2017') AND 
    (candidacy.trm_cde = '20') AND 
    (candidacy.div_cde like 'g%') and 
    (candidacy.CUR_CANDIDACY = 'n') and 
    (candidacy.ID_NUM in (SELECT candidacy.id_num  
          FROM candidacy 
          WHERE (candidacy.yr_cde = '2017') AND 
           (candidacy.trm_cde = '20') AND 
           (candidacy.div_cde like 'g%') 
          GROUP BY candidacy.id_num 
          HAVING count(candidacy.id_num) > 1)) 

Answer 1

尝试通过ROW_NUMBER函数拾取记录。要在where子句中使用行号，请进行第二个子查询。

SELECT * 
    FROM 
    (SELECT ROW_NUMBER() OVER (PARTITION BY ID_NUM ORDER BY hist_stage_dte DESC) as ROW_NUM, * 
    FROM candidacy 
    WHERE (candidacy.yr_cde = '2017') AND 
      (candidacy.trm_cde = '20') AND 
      (candidacy.div_cde like 'g%') and 
      (candidacy.CUR_CANDIDACY = 'n') and 
      (candidacy.ID_NUM in (SELECT candidacy.id_num  
           FROM candidacy 
           WHERE (candidacy.yr_cde = '2017') AND 
             (candidacy.trm_cde = '20') AND 
             (candidacy.div_cde like 'g%') 
           GROUP BY candidacy.id_num 
           HAVING count(candidacy.id_num) > 1)) 
    ) TB_AUX 
    WHERE ROW_NUM = 1 

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