在MYSQL和UNION中生成日期范围

Question

我正在尝试根据预定义的日期（截止日期）生成报告。我有两个表，进出表和加班表。

IN和OUT表

加班表

预期结果

使用UNION，它会使日期加倍，但这可以通过group by解决，但是组似乎不能在UNION中工作。

最棘手的部分是展示BLANK 6月1日和1月5日。我需要向他们展示一份时间表报告。

非常感谢任何帮助或线索

CODE：

SELECT emp_id,in,out,null 
FROM normal 
WHERE date >= '1-Jan' 
  AND date <= '10-Jan' 
  AND emp_id = '10001'
UNION
SELECT emp_id,null,null,minutes 
FROM overtime 
WHERE date >= '1-Jan' 
  AND date <= '10-Jan' 
  AND emp_id = '10001'

Answer 1

这样的事情应该做你想要的（如果我理解这个问题）：

SELECT n.date, n.emp_id, n.in, n.out, o.minutes
FROM normal n 
JOIN overtime o USING(emp_id)
WHERE n.date BETWEEN '2012-01-01' AND '2012-01-10'

请记住，如果您想显示没有匹配的日期，您必须创建一个包含此日期列表的表格：

日期

+------------+
| timestamp  |
|------------+
| 2012-01-01 |
| 2012-01-02 |
| ....       |

然后您可以通过这种方式更改查询以获得所需的结果集：

SELECT d.timestamp AS date, b.emp_id, b.in, b.out, b.minutes
FROM dates d
LEFT JOIN 
(SELECT n.date AS timestamp, n.emp_id AS emp_id, n.in AS in, n.out AS out, o.minutes AS minutes
 FROM normal n 
 JOIN overtime o USING(emp_id)
 ) b 
 USING(timestamp)
 WHERE d.timestamp BETWEEN '2012-01-01' AND '2012-01-10'

如果你想避免使用这个更复杂的查询的日期表，应该给你相同的结果，而不需要存储日期范围的第三个表：

SELECT d.timestamp AS date, b.emp_id, b.in, b.out, b.minutes
FROM ( 
SELECT '2012-01-01' + INTERVAL a + b DAY AS timestamp
FROM
(SELECT 0 a UNION SELECT 1 a UNION SELECT 2 UNION SELECT 3
UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7
UNION SELECT 8 UNION SELECT 9 ) d,
(SELECT 0 b UNION SELECT 10 UNION SELECT 20 
UNION SELECT 30 UNION SELECT 40) m
WHERE '2012-01-01' + INTERVAL a + b DAY  <  '2012-01-11'
ORDER BY a + b
) d
LEFT JOIN 
(SELECT n.date AS timestamp, n.emp_id AS emp_id, n.in AS in, n.out AS out, o.minutes AS minutes
 FROM normal n 
 JOIN overtime o USING(emp_id)
 ) b 
 USING(timestamp)