轉換行到列在MySQL V2

Question

在參考這個帖子：https://stackoverflow.com/questions/19985340/convert-rows-to-columns-in-mysql

我有這樣的代碼在那裏種加入與DIFF科拉姆名稱連接兩個表，我想我能做到這一點，這樣我可以使用bluefeet的代碼，因爲我有單獨的表，其中字符串位置在table_1上，位置ID在table_2上。它看起來像這樣

TABLE_1：

id | location 
1 | East Flow 
2 | East Level 
3 | East Pressure 
4 | East MR 
5 | West Flow 
6 | West Level 
7 | West Pressure 
8 | West MR 

表2：

locationid | val 
    1  | 10 
    2  | 20 
    3  | 30 
    4  | 40 
    5  | 100 
    6  | 200 
    7  | 300 
    8  | 400 

所以，當你執行這個查詢會是這個樣子：

SELECT id, locationid, location, val 
FROM table_1, table_2 
WHERE id = locationid 
GROUP BY id 

輸出：

id | locationid |  location | val 
1 |  1  | East Flow  | 10 
2 |  2  | East Level | 20 
3 |  3  | East Pressure | 30 
4 |  4  | East MR  | 40 
5 |  5  | West Flow  | 100 
6 |  6  | West Level | 200 
7 |  7  | West Pressure | 300 
8 |  8  | West MR  | 400 

---

我想合併@ bluefeet的代碼，我的代碼，這樣我可以用她的代碼，導致她的代碼已經工作：

select 
    substring_index(location, ' ', 1) Location, 
    max(case when location like '%Flow' then val end) Flow, 
    max(case when location like '%Level' then val end) Level, 
    max(case when location like '%Pressure' then val end) Pressure, 
    max(case when location like '%MR' then val end) MR 
from yourtable 
group by substring_index(location, ' ', 1) 

如何合併呢？選擇一個選擇或東西？ 這是我是如何希望輸出會是什麼樣子：

從這：

Location | Val | 
East Flow  | 10 | 
East Level | 20 | 
East Pressure | 30 | 
East MR  | 40 | 
West Flow  | 100 | 
West Level | 200 | 
West Pressure | 300 | 
West MR  | 400 | 

要這樣：

Location | Flow| Level | Pressure | MR | 
East  | 10 | 20 | 300 | 400 | 
West  | 100 | 200 | 300 | 400 | 

Answer 1

你應該能夠剛剛加入你的表得到的結果：

select 
    substring_index(t1.location, ' ', 1) Location, 
    max(case when t1.location like '%Flow' then t2.val end) Flow, 
    max(case when t1.location like '%Level' then t2.val end) Level, 
    max(case when t1.location like '%Pressure' then t2.val end) Pressure, 
    max(case when t1.location like '%MR' then t2.val end) MR 
from table_1 t1 
inner join table_2 t2 
    on t1.id = t2.locationid 
group by substring_index(t1.location, ' ', 1) 

見SQL Fiddle with Demo