如何使用MySQL UNION和SUM的意見

Question

我有2個表

表中的一個：

id amount 
1 2 
1 1 
2 1 

表二：

id amount 
1 2 

我想使視圖，像這樣的輸出：

查看：

id amount 
1 5 
2 1 

我試圖用我簡單的代碼，這樣

CREATE VIEW v_test AS 
SELECT id, sum(amount) 
FROM table1 
UNION ALL 
SELECT id, sum(amount) 
FROM table2 
GROUP BY id 

但是當我運行像這樣的輸出上面的SQL：

id amount 
1 2 
1 3 
2 1 

的，我想輸出的任何代碼？ 感謝

Answer 1

尋找到你的數據樣本，做的是，有些MySQL版本不允許再選擇鑑於你可以創建一個功利觀

create view v_test_union 
as 
    select id, amount 
    from table1 
    union all 
    select id, amount 
    from table2 

然後創建視圖

create view 
as 
    select id, sum(amount) 
    from v_test_union 

如果你使用的MySQL 5.7或以上，你可以在create view語句中使用子查詢：

create view 
as 
    select id, sum(amount) 
    from 
     (select id, amount 
     from table1 
     union all 
     select id, amount 
     from table2) t 
    group by id 

Answer 2

，你也可以使用這個通過加入像下面

CREATE VIEW v_test AS 
SELECT table1.id as id,(sum(table1.amount)+sum(table2.amount)) as amount FROM table1 
join table2 on table1.id=table2.id 
GROUP BY table1.id 

Answer 3

SQL DEMO

CREATE VIEW v_test AS 
SELECT id, SUM(amount) 
FROM (
     SELECT id, amount 
     FROM table1 
     UNION ALL 
     SELECT id, amount 
     FROM table2 
    ) t 
GROUP BY id  
; 

輸出