Question

在下面的查询中，我试图写一个条件来获得最小的term_cd，但这并没有给出确切的结果。任何人都可以帮助我。

要求：

对于TNT.STU_ID和TNT.MINOR_CD的每个唯一组合，请显示TNT.TERM_CD至少TNT.TERM_SEQ_NUM

代码：

SELECT
    pt.[TERM_CD]
FROM
    [SR0TNT] pt
WHERE 
    TERM_SEQ_NUM = (SELECT MIN(TERM_SEQ_NUM) 
                    FROM [SR0TNT] AS t2 
                    WHERE pt.STU_ID = t2.STU_ID
                    --and pt.TERM_CD = t2.TERM_CD
                      AND pt.STU_ID = '003899725 '

Answer 1

很少有办法真正做到这一点..这是最简单的方法之一。

SELECT
    STU_ID,
    MINOR_CD,
    [TERM_CD],
    TERM_SEQ_NUM
FROM
    (SELECT
        STU_ID,
        MINOR_CD,
        [TERM_CD],
        TERM_SEQ_NUM,
        ROW_NUMBER() OVER (PARTITION BY STU_ID,MINOR_CD ORDER BY TERM_SEQ_NUM) Rn
     FROM
        [SR0TNT]
     WHERE
        STU_ID = '003899725 '
    ) pt
WHERE
    Rn = 1

如果要使用你的方法，它会是这样的。

SELECT
    pt.[TERM_CD]
FROM
    [SR0TNT] pt
WHERE
    pt.STU_ID = '003899725 '
    AND pt.TERM_SEQ_NUM = (
        SELECT MIN(TERM_SEQ_NUM) 
        FROM [SR0TNT] AS t2 
        WHERE pt.STU_ID = t2.STU_ID AND pt.MINOR_CD = t2.MINOR_CD
    )

你也可以自己加入..

SELECT
    pt.[TERM_CD]
FROM
    [SR0TNT] pt
    JOIN (SELECT 
                STU_ID, 
                MINOR_CD, 
                MIN(TERM_SEQ_NUM) AS TERM_SEQ_NUM 
          FROM 
                [SR0TNT] 
         GROUP BY 
                STU_ID, MINOR_CD) t2 ON t2.STU_ID = pt.STU_ID 
                       AND t2.MINOR_CD = pt.MINOR_CD 
                       AND t2.TERM_SEQ_NUM = pt.TERM_SEQ_NUM 
WHERE 
    pt.STU_ID = '003899725 '

Answer 2

select pt.[TERM_CD]  --You don't need MINOR_CD as a SELECT field?
FROM [SR0TNT] pt
INNER JOIN (  --This inner join will act like a filter to exclude rows that do not have the minimum TERM_SEQ_NUM
   select TNT.TERM_CD,TNT.STU_ID,TNT.MINOR_CD, MIN(TNT.TERM_SEQ_NUM) as minm
        FROM [SR0TNT] TNT
        GROUP BY TNT.TERM_CD,TNT.STU_ID,TNT.MINOR_CD
) SUB
    ON pt.TERM_CD = SUB.TERM_CD
    AND pt.MINOR_CD = SUB.MINOR_CD
    AND pt.STU_ID = SUB.STU_ID
    AND pt.TERM_SEQ_NUM = SUB.minm
WHERE pt.STU_ID = '003899725 '

SQL：对于唯一组合，显示最小值

2 个答案: