MySQL COUNT如果在多個表之間

Question

我想根據兩個MySQL表運行相當簡單的計數，但我無法獲得正確的語法。

  Table_1        Table_2 
Actor | Behavior | Receiver |  | Behavior | Type_of_behavior | 
Eric  a  ann    a   Good 
Eric  b  ann    b   Bad 
Bob   a  Susan    a   Good 
Bob   c  Bob    c   shy 

我通過table_2.Type_of_behavior WHERE Table_1.Behavior = Table_2 Behavior和group by Table_1.Actor想COUNT Table 1.Behavior。我試過的語法如下。
我意識到我可以加入表格，但由於其他原因，我需要將它們分開。

SELECT actor, JOIN Table_1, Table_2 
COUNT(IF(Table_2.Type_of_behavior = "good", 1,0)) 
AS 'good' FROM Table_1.Behavior GROUP BY actor; 

Answer 1

我不完全確定，如果這是你想要的，但這裏的東西，你應該至少可以修改。

SELECT actor, COUNT(Type_of_behavior) 
FROM table_1 JOIN table_2 
ON table_1.behavior=table_2.behavior 
WHERE Type_of_behavior = 'good' 
GROUP BY actor 

Answer 2

SELECT actor, 
     sum(t2.Type_of_behavior = 'good') AS good 
from Table_1 t1 
join Table_2 t2 on t1.behaviour = t2.behaviour 
GROUP BY actor;