複雜的SELECT MySQL語句

Question

我遇到了從我的MySQL數據庫中選擇數據的問題。

例如，我有一個表有以下的列&表：

Table name: farming 

id | animal | amount | food 
---------------------------- 
1 | Cow | 10 | Grass 
12 | Sheep | 19 | Grass 
23 | Lion |  1 | Everything 
29 | Lamb |  3 | Grass 
102| Pig |  8 | Everything 
... 

我想從匹配food類型選擇id的是，所有行獲得amount。

E.g.如果我選擇id: 102那麼它會得到所有行food = 'Everything'

SELECT amount FROM farming WHERE food = '".$_GET['food']."' **IS THE SAME TYPE AS IT IS IN** id = '1'"; //這應該選擇10，19和amount3的amount（爲id = 1的食物類型是Grass，所以應該選擇所有行amount其中，食物類型=草。

**是我現在面臨的問題，我已經試過各種報表，似乎無法得到它的工作。

Answer 1

您可以通過子句將總結使用組一個從量塔11值whre食品= '草'

SELECT SUM(amount) ammount FROM farming 
     WHERE food = (select food FROM farming where id = 102) 
     GROUP BY food 

Answer 2

這應該做的伎倆

select amount 
from farming 
where food = (
      select food 
      from farming 
      where id = 1 
     )