條件語句，骨料跨多個表

Question

我有表如下所示：

`units` 
+----+------+-------+---------------+-------+ 
| id | tech | jobID |  city  | units | 
+----+------+-------+---------------+-------+ 
| 1 | 1234 | 8535 | San Jose  |  3 | 
| 2 | 1234 | 8253 | San Francisco |  4 | 
| 3 | 1234 | 2457 | San Francisco |  5 | 
| 4 | 1234 | 8351 | Mountain View |  8 | 
+----+------+-------+---------------+-------+ 

，並使用這些數據做一些計算的看法：

`total` 
+----+--------+------+-------+ 
| id | name | tech | total | 
+----+--------+------+-------+ 
| 1 | Dan | 1234 | 12 | 
| 2 | Dan SF | 1234 | 12 | 
+----+--------+------+-------+ ... 

我的問題是，我試圖總結Dan在舊金山完成的單位數量以及他在其他地方完成的單位數量（需要專門跟蹤SF中完成的單位數量）。但是，我不確定如何在我的選擇查詢中執行此操作，並且如果您查看當前的總表，則會看到兩個總值都只是將所有單位相加，而不考慮城市。

我希望得到以下幾點：

`total` 
+----+--------+------+-------+ 
| id | name | tech | total | 
+----+--------+------+-------+ 
| 1 | Dan | 1234 | 11 | 
| 2 | Dan SF | 1234 |  9 | 
+----+--------+------+-------+ ... 

我需要幫助寫我的選擇，因爲我不能確定如何使用CASE以獲得期望的結果。我試過以下內容：

SELECT otherTable.name AS name, units.tech AS tech, 
(CASE WHEN City = 'SAN FRANCISCO' THEN SUM(units) 
     ELSE SUM(units) 
) AS total 
FROM units, otherTable 
GROUP BY name 

但很明顯，這是行不通的，因爲我沒有區分兩個集合中的城市。

任何幫助，非常感謝。

編輯：我目前的觀點的SELECT查詢（與加盟信息）如下：

`otherTable` 
+----+--------+------+-----------+ 
| id | name | tech | otherInfo | 
+----+--------+------+-----------+ 
| 1 | Dan | 1234 | ...... | 
+----+--------+------+-----------+ 

Answer 1

：

SELECT otherTable.name, units.tech, SUM(units.units) 
FROM units 
LEFT JOIN otherTable ON otherTable.tech = units.tech 
GROUP BY name 

至於otherTable，它只是每個高科技ID與一個名字相關聯首先，看起來您的基本查詢是錯誤的。 units和otherTable之間並沒有任何關係，但我不知道足夠。

對我來說，看起來很奇怪，你希望它分成行而不是列，但你可以請執行以下操作：

SELECT otherTable.name AS name, units.tech AS tech, 
SUM(units) AS total 
FROM units, otherTable 
-- not sure if this section should exclude 'SAN FRANCISO' or not 
GROUP BY name 
UNION ALL 
SELECT otherTable.name || ' SF' AS name, units.tech AS tech, 
SUM(units) AS total 
FROM units, otherTable 
WHERE City = 'SAN FRANCISCO' 
GROUP BY name 

這將使你

+--------+------+-------+ 
| name | tech | total | 
+--------+------+-------+ 
| Dan | 1234 | 11 | 
| Dan SF | 1234 |  9 | 
+--------+------+-------+ 

或者，如果你想單獨的列，你可以這樣做

SELECT otherTable.name AS name, units.tech AS tech, 
SUM(units) AS total, 
SUM(CASE WHEN City = 'SAN FRANCISCO' THEN units 
     ELSE 0 
) AS sf_total 
FROM units, otherTable 
GROUP BY name 

這將使你

+--------+------+-------+----------+ 
| name | tech | total | sf_total | 
+--------+------+-------+----------+ 
| Dan | 1234 | 11 |  9 | 
+--------+------+-------+----------+