在Mysql中的具體查詢

Question

我有兩個表reports和holidays。

reports：(username varchar(30),activity varchar(30),hours int(3),report_date date)

holidays：(holiday_name varchar(30), holiday_date date)

select * from reports給

+----------+-----------+---------+------------+ 
| username | activity | hours | date  | 
+----------+-----------+---------+------------+ 
| prasoon | testing | 3 | 2009-01-01 | 
| prasoon | coding | 4 | 2009-01-03 | 
| prasoon | designing| 2 | 2009-01-04 | 
| prasoon | coding | 4 | 2009-01-06 | 
+----------+-----------+---------+------------+ 

select * from holidays給

+--------------+---------------+ 
| holiday_name | holiday_date | 
+--------------+---------------+ 
| Diwali  | 2009-01-02 | 
| Holi   | 2009-01-05 | 
+--------------+---------------+ 

有什麼辦法通過我可以輸出以下內容？

+-------------+-----------+---------+-------------------+ 
| date  | activity | hours | holiday_name  | 
+-------------+-----------+---------+-------------------+ 
| 2009-01-01 | testing | 3 |     | 
| 2009-01-02 |   |   |  Diwali  | 
| 2009-01-03 | coding | 4 |     | 
| 2009-01-04 | designing| 2 |     | 
| 2009-01-05 |   |   |  Holi   | 
| 2009-01-06 | coding | 4 |     | 
+-------------+-----------+---------+-------------------+ 

Answer 1

SELECT date, 
     activity, 
     hours, 
     '' AS holiday_name 
FROM reports 
WHERE date >= '2008-12-1' 
     AND date < '2009-1-4' 
UNION 
(SELECT holiday_date, 
     '', 
     '', 
     holiday_name 
FROM holidays 
WHERE holiday_date >= '2008-12-1' 
     AND holiday_date < '2009-1-4') 
ORDER BY date 

Answer 2

select * from 
    (select h.holdiday_date as date from holiday h 
     union 
     select r.date as date from reports r) dates 
left join holiday h1 on (h1.holiday_date = dates.date) 
left join reports r1 on (r1.date = dates.date) 
order by dates.date 

總之你聯合你有一個子查詢，比左邊的日期加入到兩個表。