SQL Group by max

Question

我正在使用MariaDB 5.5，並且在選擇查詢時出現問題。我試圖選擇一列中兩個日期時間之間的值的行，並按另一列中的最大日期時間分組。表結構是一樣的東西

|   Model_Init |   Model_Time | Location_ID | Var_ID | Value | 
| ------------------- | ------------------- | ------------| ------ | ----- | 
| 2014-08-22 06:00:00 | 2014-08-23 04:00:00 |  123456 |  23 | 76.2 | 
| 2014-08-22 06:00:00 | 2014-08-23 05:00:00 |  123456 |  23 | 77.2 | 
| 2014-08-22 06:00:00 | 2014-08-23 06:00:00 |  123456 |  23 | 78.2 | 
| 2014-08-22 06:00:00 | 2014-08-23 07:00:00 |  123456 |  23 | 79.2 | 
| 2014-08-22 06:00:00 | 2014-08-23 08:00:00 |  123456 |  23 | 80.2 | 
| 2014-08-23 06:00:00 | 2014-08-23 06:00:00 |  123456 |  23 | 81.2 | 
| 2014-08-23 06:00:00 | 2014-08-23 07:00:00 |  123456 |  23 | 82.2 | 
| 2014-08-23 06:00:00 | 2014-08-23 08:00:00 |  123456 |  23 | 83.2 | 
| 2014-08-23 06:00:00 | 2014-08-23 09:00:00 |  123456 |  23 | 84.2 | 
| 2014-08-23 06:00:00 | 2014-08-23 10:00:00 |  123456 |  23 | 85.2 | 
| 2014-08-23 06:00:00 | 2014-08-23 11:00:00 |  123456 |  23 | 86.2 | 

我想選擇兩個Model_Time值之間的時間連續組，即：

SELECT * 
FROM WRF_data_norm 
WHERE Location_ID=123456 AND 
     Var_ID=23 AND 
     Model_Time>='2014-08-23 04:00:00' AND 
     Model_Time<='2014-08-23 10:00:00' 
GROUP BY Model_Time; 

可能返回結果：

|   Model_Init |   Model_Time | Location_ID | Var_ID | Value | 
| ------------------- | ------------------- | ------------| ------ | ----- | 
| 2014-08-22 06:00:00 | 2014-08-23 04:00:00 |  123456 |  23 | 76.2 | 
| 2014-08-22 06:00:00 | 2014-08-23 05:00:00 |  123456 |  23 | 77.2 | 
| 2014-08-22 06:00:00 | 2014-08-23 06:00:00 |  123456 |  23 | 78.2 | 
| 2014-08-22 06:00:00 | 2014-08-23 07:00:00 |  123456 |  23 | 79.2 | 
| 2014-08-22 06:00:00 | 2014-08-23 08:00:00 |  123456 |  23 | 80.2 | 
| 2014-08-23 06:00:00 | 2014-08-23 09:00:00 |  123456 |  23 | 84.2 | 
| 2014-08-23 06:00:00 | 2014-08-23 10:00:00 |  123456 |  23 | 85.2 | 
| 2014-08-23 06:00:00 | 2014-08-23 11:00:00 |  123456 |  23 | 86.2 | 

在哪裏需要Model_Time與Model_Init的最大值不同的值，即：

|   Model_Init |   Model_Time | Location_ID | Var_ID | Value | 
| ------------------- | ------------------- | ------------| ------ | ----- | 
| 2014-08-22 06:00:00 | 2014-08-23 04:00:00 |  123456 |  23 | 76.2 | 
| 2014-08-22 06:00:00 | 2014-08-23 05:00:00 |  123456 |  23 | 77.2 | 
| 2014-08-23 06:00:00 | 2014-08-23 06:00:00 |  123456 |  23 | 81.2 | 
| 2014-08-23 06:00:00 | 2014-08-23 07:00:00 |  123456 |  23 | 82.2 | 
| 2014-08-23 06:00:00 | 2014-08-23 08:00:00 |  123456 |  23 | 83.2 | 
| 2014-08-23 06:00:00 | 2014-08-23 09:00:00 |  123456 |  23 | 84.2 | 
| 2014-08-23 06:00:00 | 2014-08-23 10:00:00 |  123456 |  23 | 85.2 | 
| 2014-08-23 06:00:00 | 2014-08-23 11:00:00 |  123456 |  23 | 86.2 | 

我不知道如何改變查詢。

編輯：找到解決方案：

SELECT Max(Model_Init), Model_Time,Location_ID, Var_ID,Value FROM WRF_data_norm GROUP BY Model_Time, Location_ID, Var_ID, Value HAVING Location_ID=123456 AND Var_ID=23 AND Model_Time>='2014-09-23 04:00:00' AND Model_Time<='2014-09-23 11:00:00' ORDER BY Model_Time;

Answer 1

試試這個： -

SELECT Model_Init, Model_Time, Location_ID, Var_ID, MAX(Value) 
FROM WRF_data_norm 
WHERE Location_ID=123456 AND 
Var_ID=23 AND 
Model_Time>='2014-08-23 04:00:00' AND 
Model_Time<='2014-08-23 10:00:00' 
GROUP BY Model_Init, Model_Time, Location_ID, Var_ID; 

這可能會對你有所幫助。