mysql - 向查询中添加列

Question

我有这张桌子

user_id     time_completed
    4           86.30887
    5           57.81364
    5           35.50281
    5           10.00000
    5           74.19355
    5           31.91489
    6           15.00000
    6           20.50000

我总结时间并替换另一个表（db_users）中的用户：

id          username        country
1           admin           ES
2           peter           IT
3           tom             US
4           user            GB
5           joey            GE
6           helen           FR

但我也需要国家行也出现：

user_id     time_completed      country
joey           209.42489            GE
user           86.30887             GB
helen           35.50000            FR

看看这里：http ://sqlfiddle.com/#!2/24d1b/11

Answer 1

您只需添加该字段：

SELECT b.username, SUM(time_COmpleted) totalTime, b.country
FROM tableName a 
      INNER JOIN  db_users b
        ON (a.user_id = b.id)
GROUP BY b.username, b.country

请参阅带有演示的 SQL Fiddle

Answer 2

在这里，只添加缺少的字段

SELECT b.username, SUM(time_COmpleted) totalTime, b.country
FROM tableName a 
      INNER JOIN  db_users b
        ON (a.user_id = b.id)
GROUP BY b.username, b.country

SQLFiddle 演示

根据您的演示，所有用户都生活在GB

Answer 3

好吧，只需将国家添加到SELECT：

SELECT b.username, SUM(time_COmpleted) totalTime, b.country
FROM tableName a 
    INNER JOIN  db_users b
    ON (a.user_id = b.id)
GROUP BY b.username