SELECT * FROM表中的兩個和count（coulmn_name）FROM表一個

Question

如何選擇* FROM表中的兩個和count（t_type）FROM表的一個WHERE表一和二的物種都是平等的

表一個=樹

id | t_type 
~~~~~~~~~~~~ 
1 | Tree one 
2 | Tree two 
3 | Tree Three 
4 | Tree Four 
5 | Tree one 

表2 =請求

id | req_species 
~~~~~~~~~~~~ 
1 | Tree one 
2 | Tree two 
3 | Tree one 
4 | Tree two 

返回的表將具有相同的行數作爲表的兩個（請求），在這種情況下4排。

期望輸出

species | Qunatity 
~~~~~~~~~~~~ 
Tree one | 2 
Tree two | 1 
Tree one | 2 
Tree two | 1 

Answer 1

一種方法是使用相關子查詢：

select r.species, 
     (select count(*) from trees t where t.species = r.species) as quantity 
from requests r; 

Answer 2

SELECT COUNT(T1.t_type) AS QUALITY,T1.t_type 
FROM TABLE_1 AS T1 WHERE T1.t_type IN 
    (SELECT T2.req_species FROM TABLE_2 AS T2) 

GROUP BY T1.t_type