我應該在這裏使用一個內部聯接（MySQL的）

Question

我有兩個表：

t1: 

cust_id  email 
201   email1@sadpanda.com 
202   email2@email.com 
203   email3@sadpanda.com 


t2: 

cust_id  value 
201   dfceaa64f8b93661903a849b09c5ac4e10abdfed21763a04d6eb9523e02d6dc1:Qs 
202   c15af11e5acb2f6b7e7b12ab7eee8ce482f0cf76f76b7e65dde6b15c3a910680:Qx 
203   71ae98d020b16f6f668db6bde3f9c18350a892b55736995237fa71aa5dc2b206:MU 

我想從「T1」，其中電子郵件是像「sadpanda」選擇和接受的值從這些用戶'T2'。我應該使用內部連接嗎？

Answer 1

SELECT t2.* 
FROM t2 
JOIN t1 USING (cust_id) 
WHERE t1.email = 'email3@sadpanda.com' 

SQL Fiddle example

Answer 2

你可以有兩種方法可以做到這一點 1.您可以使用簡單的連接查詢。像

SELECT T2.* 
FROM T1 JOIN T2 ON T.CUST_ID = T2.CUST_ID 
WHERE T1.EMAIL LIKE '%sadpanda%' 

1. ，或者您可以使用子查詢類似

   SELECT T2 * FROM T2 WHERE CUST_ID IN（SELECT CUST_ID FROM T1 WHERE T1.EMAIL LIKE '％sadpanda％'）

我建議第一個。它會跑得更快，然後第二個。