如何通过最早的日期sql获取平均值？

这是我的桌子：

CREATE TABLE Consultation (
idConsultation number,
dateConsultation date NOT NULL,
prixConsultation number(4,2),
pouls number(3),
size number(3),
poids number(3),
pressionSystolique number(3),
pressionDiastolique number(3),
idMedecin number(3),
idPatient number(3),
);

患者可以多次出现在此表中，并且会诊有日期

因此，我希望得到平均规模，并尊重这样一个事实，即我们只能对每位患者采用较旧的咨询日期

提前谢谢，这是我带来的，但没有工作

SELECT AVG(size)
FROM Consultation
WHERE dateConsultation = (SELECT MAX(dateConsultation) FROM Consultation);

---

您希望首先获得每个

idPatient

的

max（dateConsultation）

，然后使用该值筛选您的

avg（size）

选择。您可以使用子查询和
内部联接来执行此操作：

select avg(c.size) as avgSizeLatestConsultation
from Consultation as c
    inner join (select
                    idPatient,
                    max(dateConsultation) as LatestConsultation
                from Consultation
                group by
                    idPatient) as d
         on d.idPatient = c.idPatient
         and d.LatestConsultation = c.dateConsultation

鉴于此测试数据：

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(1,  10, TO_DATE('01-FEB-2015', 'DD-MON-YYYY'), 1);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(2,  10, TO_DATE('02-FEB-2015', 'DD-MON-YYYY'), 3);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(3,  11, TO_DATE('03-FEB-2015', 'DD-MON-YYYY'), 1);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(4,  12, TO_DATE('04-FEB-2015', 'DD-MON-YYYY'), 1);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(5,  13, TO_DATE('05-FEB-2015', 'DD-MON-YYYY'), 1);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(6,  13, TO_DATE('06-FEB-2015', 'DD-MON-YYYY'), 2);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(7,  13, TO_DATE('07-FEB-2015', 'DD-MON-YYYY'), 3);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(8,  14, TO_DATE('08-FEB-2015', 'DD-MON-YYYY'), 1);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(9,  15, TO_DATE('09-FEB-2015', 'DD-MON-YYYY'), 1);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(10, 15, TO_DATE('10-FEB-2015', 'DD-MON-YYYY'), 12);

以下查询生成正确的结果（
AVG_SIZE=1
）：


分享和享受。
列
taille
在哪里？请澄清，您想要某个条件还是对结果进行聚合？不太清楚您在这里要问什么，也许您可以显示一些示例数据和预期结果集。较旧的日期将是MIN（DateColumn），MAX（DateColumn）将为您提供最新的日期。另外，如果您选择一个最早或最晚日期的值，则平均值将是该值本身，不确定您试图通过该值实现什么。在这种情况下，我已正确回答了您的问题。FROM关键字not found where expected？Oracle，SQL developer
INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(1,  10, TO_DATE('01-FEB-2015', 'DD-MON-YYYY'), 1);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(2,  10, TO_DATE('02-FEB-2015', 'DD-MON-YYYY'), 3);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(3,  11, TO_DATE('03-FEB-2015', 'DD-MON-YYYY'), 1);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(4,  12, TO_DATE('04-FEB-2015', 'DD-MON-YYYY'), 1);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(5,  13, TO_DATE('05-FEB-2015', 'DD-MON-YYYY'), 1);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(6,  13, TO_DATE('06-FEB-2015', 'DD-MON-YYYY'), 2);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(7,  13, TO_DATE('07-FEB-2015', 'DD-MON-YYYY'), 3);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(8,  14, TO_DATE('08-FEB-2015', 'DD-MON-YYYY'), 1);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(9,  15, TO_DATE('09-FEB-2015', 'DD-MON-YYYY'), 1);

INSERT INTO CONSULTATION (IDCONSULTATION, IDPATIENT, DATECONSULTATION, "size")
  VALUES(10, 15, TO_DATE('10-FEB-2015', 'DD-MON-YYYY'), 12);

SELECT AVG("size") AS AVG_SIZE
  FROM CONSULTATION
  WHERE IDCONSULTATION IN (SELECT IDCONSULTATION
                             FROM CONSULTATION
                             WHERE (IDPATIENT, DATECONSULTATION) IN
                               (SELECT IDPATIENT, MIN(DATECONSULTATION) AS DATECONSULTATION
                                  FROM CONSULTATION
                                  GROUP BY IDPATIENT));