Sql 显示最旧或最新的记录，但不显示日期

我有以下表格：

账户

+------------+--------------+ | account_id | account_name | +------------+--------------+ | 452 | a | | 785 | b | | 985 | c | +------------+--------------+ 我需要显示表

task

和

account

中的记录，以便只显示最早的任务，而不显示日期。因此，结果将是：

+--------------+---------+ | account_name | task_id | +--------------+---------+ | a | 2 | | b | 7 | | c | 4 | +--------------+---------+

---

您可以简单地使用子查询：

SELECT S.ACCOUNT_NAME, S.TASK_ID FROM (
  SELECT A.ACCOUNT_NAME, T.TASK_ID, MIN(T.TASK_DATE)
  FROM ACCOUNT A
  INNER JOIN TASK T
  ON A.ACCOUNT_ID = T.ACCOUNT_ID
  GROUP BY ACCOUNT_NAME, TASK_ID
) S

---

您可以简单地使用子查询：

SELECT S.ACCOUNT_NAME, S.TASK_ID FROM (
  SELECT A.ACCOUNT_NAME, T.TASK_ID, MIN(T.TASK_DATE)
  FROM ACCOUNT A
  INNER JOIN TASK T
  ON A.ACCOUNT_ID = T.ACCOUNT_ID
  GROUP BY ACCOUNT_NAME, TASK_ID
) S

---

也许是这样的：

WITH CTE
AS
(
    SELECT 
        A.ACCOUNT_NAME, 
        T.TASK_ID, 
        ROW_NUMBER() OVER(PARTITION BY T.TASK_ID 
                     ORDER BY T.TASK_DATE DESC) AS RowNbr
    FROM ACCOUNT A
    INNER JOIN TASK T
    ON A.ACCOUNT_ID = T.ACCOUNT_ID
)
SELECT
    CTE.ACCOUNT_NAME,
    CTE.TASK_ID
FROM
    CTE
WHERE 
    CTE.RowNbr=1;

---

也许是这样的：

WITH CTE
AS
(
    SELECT 
        A.ACCOUNT_NAME, 
        T.TASK_ID, 
        ROW_NUMBER() OVER(PARTITION BY T.TASK_ID 
                     ORDER BY T.TASK_DATE DESC) AS RowNbr
    FROM ACCOUNT A
    INNER JOIN TASK T
    ON A.ACCOUNT_ID = T.ACCOUNT_ID
)
SELECT
    CTE.ACCOUNT_NAME,
    CTE.TASK_ID
FROM
    CTE
WHERE 
    CTE.RowNbr=1;

---

您可以使用分析：

SELECT account_name, task_id
  FROM (SELECT a.account_name,
               t.task_id,
               row_number() 
                  over(PARTITION BY a.account_id ORDER BY t.task_date) task_num
          FROM account a
         INNER JOIN task t ON a.account_id = t.account_id
         GROUP BY account_name, task_id)
 WHERE task_num = 1

或自联接：

SELECT a.account_name, t.task_id
  FROM account a
 INNER JOIN task t ON a.account_id = t.account_id
 WHERE (t.account_id, t.task_date) = (SELECT t_in.account_id, 
                                             MIN(t_in.task_date) 
                                         FROM task t_in 
                                        GROUP BY t_in.account_id)

---

您可以使用分析：

SELECT account_name, task_id
  FROM (SELECT a.account_name,
               t.task_id,
               row_number() 
                  over(PARTITION BY a.account_id ORDER BY t.task_date) task_num
          FROM account a
         INNER JOIN task t ON a.account_id = t.account_id
         GROUP BY account_name, task_id)
 WHERE task_num = 1

或自联接：

SELECT a.account_name, t.task_id
  FROM account a
 INNER JOIN task t ON a.account_id = t.account_id
 WHERE (t.account_id, t.task_date) = (SELECT t_in.account_id, 
                                             MIN(t_in.task_date) 
                                         FROM task t_in 
                                        GROUP BY t_in.account_id)

---

您可以使用以下简单方法：

SELECT a.account_name, t.task_id
FROM   account a,
       task t
WHERE  a.account_id= t.account_id 
AND    t.task_date in (SELECT MIN(t.task_date))
GROUP BY account_name, task_id;

---

您可以使用以下简单方法：

SELECT a.account_name, t.task_id
FROM   account a,
       task t
WHERE  a.account_id= t.account_id 
AND    t.task_date in (SELECT MIN(t.task_date))
GROUP BY account_name, task_id;

---

另一种方法，稍微短一点：

select max(a.accountname) as account_name
     , max(t.taskid) keep(dense_rank first
                               order by t.taskdate) as task_id
 from account1 a
 join task t
   on (a.accountid = t.accountid)
group by a.accountid

结果:

ACCOUNT_NAME    TASK_ID
------------ ----------
a                     2
b                     7
c                     4

---

另一种方法，稍微短一点：

select max(a.accountname) as account_name
     , max(t.taskid) keep(dense_rank first
                               order by t.taskdate) as task_id
 from account1 a
 join task t
   on (a.accountid = t.accountid)
group by a.accountid

结果:

ACCOUNT_NAME    TASK_ID
------------ ----------
a                     2
b                     7
c                     4

---

这比看起来容易：在正常连接表之后，只需按max（tak_date）进行过滤，您可以通过简单的子选择进行计算

SELECT acc.account_name, tsk.task_id
FROM account acc
JOIN task    tsk on (acc.account_id = tsk.account_id)
WHERE tsk.task_date = (
  SELECT MAX(aux.task_date)
  FROM task aux
  WHERE aux.account_id = tsk.account_id 
)

---

这比看起来更容易：在正常连接表之后，只需按max（tak_date）进行过滤，您可以通过简单的子选择进行计算

SELECT acc.account_name, tsk.task_id
FROM account acc
JOIN task    tsk on (acc.account_id = tsk.account_id)
WHERE tsk.task_date = (
  SELECT MAX(aux.task_date)
  FROM task aux
  WHERE aux.account_id = tsk.account_id 
)

---

SELECT MIN（t.task\u date）

不是有效的Oracle SELECT语句。与MS SQL Server不同，在Oracle中，您总是必须从某处进行选择，这意味着

FROM

子句是必需的。@NicholasKrasnov我是用mysql在头脑中编写查询的。但是如果您愿意，您可以在子查询中包含“FROM task”。

select MIN（t.task\u date）

不是有效的Oracle select语句。与MS SQL Server不同，在Oracle中，您总是必须从某个地方进行选择，这意味着

FROM

子句是必需的。@NicholasKrasnov我是用mysql在头脑中编写查询的。但是如果您愿意，可以在子查询中包含“FROM task”。我尝试了自连接，效果非常好。除了简单之外。ThanksI尝试了自连接，效果非常好。除了简单之外。谢谢