的Oracle SQL子查詢

Question

我想選擇誰已經比平均總時間，任何人都已經工作，一個陣營

表是人與計劃工作較少的人

這是我到目前爲止有：

SELECT fname AS "First Name", lname AS "Last Name", 
SUM((end_time - start_time) * 24)   
FROM person JOIN schedule USING (person_ID) 
GROUP BY fname 
HAVING SUM((end_time - start_time) * 24) < (
SELECT AVG(SUM((end_time - start_time) * 24)) FROM schedule);` 

人有FNAME，LNAME和PERSON_ID 時間表sched_id，s_date，START_TIME，END_TIME和PERSON_ID

謝謝！

收到此錯誤：

Error starting at line 18 in command: 
    SELECT fname AS "First Name", lname AS "Last Name", 
    SUM((end_time - start_time) * 24)  
    FROM person JOIN schedule USING (person_ID) 
    GROUP BY fname 
    HAVING SUM((end_time - start_time) * 24) < (
    SELECT AVG(SUM((end_time - start_time) * 24)) FROM schedule) 
    Error at Command Line:18 Column:31 
    Error report: 
    SQL Error: ORA-00979: not a GROUP BY expression 
    00979. 00000 - "not a GROUP BY expression" 
    *Cause:  
    *Action: 

Answer 1

本集團需要包括在你的SELECT語句中的所有非聚集的領域（所以一切除了SUM（）在這種情況下）。

嘗試將其更改爲：

GROUP BY fname, lname 

Answer 2

當使用聚合函數，如SUM，您將需要通過包括該組中的所有非集合屬性：

SELECT fname AS "First Name", lname AS "Last Name", 
SUM((end_time - start_time) * 24)   
FROM person JOIN schedule USING (person_ID) 
GROUP BY fname, lname --this is changed 
HAVING SUM((end_time - start_time) * 24) < (
SELECT AVG(SUM((end_time - start_time) * 24)) FROM schedule);` 

Answer 3

我想解決此問題的最佳方法是使用分析函數：

select "First Name", "Last Name", hours 
from (SELECT fname AS "First Name", lname AS "Last Name", 
      SUM((end_time - start_time) * 24) as hours, 
      avg(SUM((end_time - start_time) * 24)) over() as avghours 
     FROM person JOIN 
      schedule 
      USING (person_ID) 
     GROUP BY fname, lname 
    ) t 
WHERE hours < avghours; 

報告的特定問題Oracle是avg(sum())不允許用於group by（除非，如上所述，avg()實際上是一個分析函數）。