MySQL查詢通過contigious外鍵值

Question

我有數據這樣的分組：

+----+-------------------------+----------+----------+ 
| ID |  DateReceived  | Quantity | VendorID | 
+----+-------------------------+----------+----------+ 
| 1 | 2010-08-09 06:53:44.783 |  2 |  1 | 
| 2 | 2010-08-01 13:31:26.893 |  1 |  1 | 
| 3 | 2010-07-26 07:52:29.403 |  2 |  1 | 
| 4 | 2011-03-22 13:31:11.000 |  1 |  2 | 
| 5 | 2011-03-22 13:31:11.000 |  1 |  2 | 
| 6 | 2011-03-22 11:27:01.000 |  1 |  2 | 
| 7 | 2011-03-18 09:04:58.000 |  1 |  1 | 
| 8 | 2011-12-17 08:21:29.000 |  1 |  3 | 
| 9 | 2012-08-10 10:55:20.000 |  9 |  3 | 
| 10 | 2012-08-02 20:18:10.000 |  5 |  1 | 
| 11 | 2012-07-12 20:44:36.000 |  3 |  1 | 
| 12 | 2012-07-05 20:45:29.000 |  1 |  1 | 
| 13 | 2013-03-22 13:31:11.000 |  1 |  2 | 
| 14 | 2013-03-22 13:31:11.000 |  1 |  2 | 
+----+-------------------------+----------+----------+ 

我想通過DateReceived對數據進行排序，總結了Quantity。但是，只要它們相鄰（當按DateReceived排序時），我想要將Quantity總和爲VendorID，如下面的示例輸出。

+----------+----------+ 
| VendorID | Quantity | 
+----------+----------+ 
|  1 |  5 | 
|  2 |  3 | 
|  1 |  1 | 
|  3 |  10 | 
|  1 |  9 | 
|  2 |  2 | 
+----------+----------+ 

我認爲答案與變量有關，但我不知道如何去做。

什麼是MySQL查詢來生成所需的輸出？

注意：我問exact same thing here但是對於MS Sql，我現在需要這個用於MySQL。

Answer 1

select 
VendorID, 
SUM(Quantity) 
from (
select 
t.*, 
@grn := if(@prev != VendorID, @grn + 1, @grn) as grn, 
@prev := VendorID 
from 
t 
, (select @grn := 0, @prev := null) var_init 
order by DateReceived 
) sq 
GROUP BY grn 

但您的預期輸出是錯誤的。你可以通過執行看到這只是這一點：

select 
t.*, 
@grn := if(@prev != VendorID, @grn + 1, @grn) as grn, 
@prev := VendorID 
from 
t 
, (select @grn := 0, @prev := null) var_init 
order by DateReceived 

導致：整個查詢的

| ID |     DATERECEIVED | QUANTITY | VENDORID | GRN | @PREV := VENDORID | 
|----|---------------------------------|----------|----------|-----|-------------------| 
| 3 |  July, 26 2010 07:52:29+0000 |  2 |  1 | 0 |     1 | 
| 2 | August, 01 2010 13:31:26+0000 |  1 |  1 | 0 |     1 | 
| 1 | August, 09 2010 06:53:44+0000 |  2 |  1 | 0 |     1 | 
| 7 | March, 18 2011 09:04:58+0000 |  1 |  1 | 0 |     1 | 
| 6 | March, 22 2011 11:27:01+0000 |  1 |  2 | 1 |     2 | 
| 4 | March, 22 2011 13:31:11+0000 |  1 |  2 | 1 |     2 | 
| 5 | March, 22 2011 13:31:11+0000 |  1 |  2 | 1 |     2 | 
| 8 | December, 17 2011 08:21:29+0000 |  1 |  3 | 2 |     3 | 
| 12 |  July, 05 2012 20:45:29+0000 |  1 |  1 | 3 |     1 | 
| 11 |  July, 12 2012 20:44:36+0000 |  3 |  1 | 3 |     1 | 
| 10 | August, 02 2012 20:18:10+0000 |  5 |  1 | 3 |     1 | 
| 9 | August, 10 2012 10:55:20+0000 |  9 |  3 | 4 |     3 | 
| 13 | March, 22 2013 13:31:11+0000 |  1 |  2 | 5 |     2 | 
| 14 | March, 22 2013 13:31:11+0000 |  1 |  2 | 5 |     2 | 

結果：

| VENDORID | SUM(QUANTITY) | 
|----------|---------------| 
|  1 |    6 | 
|  2 |    3 | 
|  3 |    1 | 
|  1 |    9 | 
|  3 |    9 | 
|  2 |    2 | 

• sqlfiddle