MySQL從兩個表中獲取數據

Question

我在從兩個表中獲取我想要的結果時遇到問題

table #1: history

  customer_id  |  Action
 ------------------------
  217          |  buy
 ------------------------
  218          |  sell
 ------------------------
  219          |  hold
 ------------------------

 table #2: Customers

  customer_id    |  name
 ----------------------------
  217            |  Alan
 ----------------------------
  218            |  Jan
 ----------------------------
  219            |  Rick

我現在有一個很長的查詢，但本質上我想添加以使名稱與金額匹配。 我試過了，但是沒有用：

(SELECT action AS action FROM "history` LEFT JOIN ON " customer(customer_id=customer_id)`)

我對查詢不是很熟悉，因此不勝感激

Answer 1

應該是這樣的：

SELECT h.Action AS action
   FROM history h
   LEFT JOIN Customers c
   ON h.customer_id = c.customer_id

您要么需要指定表，要么創建一個別名以與列/數據相關聯。

Answer 2

是一個簡單的連接

select action
from  history
left join Customers on Customers.Customer_id = history.customer_id

你可以確認使用

select history.customer_id, Customers.Customer_id history.action , Customers.name
from  history
left join Customers on Customers.Customer_id = history.customer_id

Answer 3

您可以像這樣聯接表：

SELECT history.action AS Action ,Customers.name AS Name
FROM `history`
LEFT JOIN `Customers` ON history.customer_id = Customers.customer_id;