我正在使用this example database我从两个不同的表运行以下查询
mysql> select * from salaries where emp_no=10017;
+--------+--------+------------+------------+
| emp_no | salary | from_date | to_date |
+--------+--------+------------+------------+
| 10017 | 71380 | 1993-08-03 | 1994-08-03 |
| 10017 | 75538 | 1994-08-03 | 1995-08-03 |
| 10017 | 79510 | 1995-08-03 | 1996-08-02 |
| 10017 | 82163 | 1996-08-02 | 1997-08-02 |
| 10017 | 86157 | 1997-08-02 | 1998-08-02 |
| 10017 | 89619 | 1998-08-02 | 1999-08-02 |
| 10017 | 91985 | 1999-08-02 | 2000-08-01 |
| 10017 | 96122 | 2000-08-01 | 2001-08-01 |
| 10017 | 98522 | 2001-08-01 | 2002-08-01 |
| 10017 | 99651 | 2002-08-01 | 9999-01-01 |
+--------+--------+------------+------------+
10 rows in set (0.01 sec)
mysql> select * from titles where emp_no=10017;
+--------+--------------+------------+------------+
| emp_no | title | from_date | to_date |
+--------+--------------+------------+------------+
| 10017 | Senior Staff | 2000-08-03 | 9999-01-01 |
| 10017 | Staff | 1993-08-03 | 2000-08-03 |
+--------+--------------+------------+------------+
2 rows in set (0.01 sec)
现在我想要的是连接这两个表，以便得到下表
emp_no title salary years
10017 Staff 71380 1993
10017 Staff 75538 1994
10017 Staff 79510 1995
10017 Staff 82163 1996
10017 Staff 86157 1997
10017 Staff 89619 1998
10017 Staff 91985 1999
10017 Staff 96122 2000
10017 Staff 98522 2001
10017 Senior Staff 99651 2002
但是我尝试连接这两个表，我得到如下重复值，这是合乎逻辑的，因为表 2 中的 2 个值与表 1 中的 10 个值相关。我还尝试使用 from_date 连接多个列，但您可以看到日期略有不同，所以我不能这样做。
mysql> select salaries.emp_no, titles.title, salaries.salary, salaries.from_date
from titles
inner join salaries
on salaries.emp_no = titles.emp_no
where salaries.emp_no=10017;
emp_no title salary from_date
10017 Senior Staff 71380 1993-08-03
10017 Senior Staff 75538 1994-08-03
10017 Senior Staff 79510 1995-08-03
10017 Senior Staff 82163 1996-08-02
10017 Senior Staff 86157 1997-08-02
10017 Senior Staff 89619 1998-08-02
10017 Senior Staff 91985 1999-08-02
10017 Senior Staff 96122 2000-08-01
10017 Senior Staff 98522 2001-08-01
10017 Senior Staff 99651 2002-08-01
10017 Staff 71380 1993-08-03
10017 Staff 75538 1994-08-03
10017 Staff 79510 1995-08-03
10017 Staff 82163 1996-08-02
10017 Staff 86157 1997-08-02
10017 Staff 89619 1998-08-02
10017 Staff 91985 1999-08-02
10017 Staff 96122 2000-08-01
10017 Staff 98522 2001-08-01
10017 Staff 99651 2002-08-01
我的问题:在没有其他方法链接它们的情况下，我怎样才能获得所需的结果？或者有什么我忘记了？
最佳答案
检查日期是否重叠:
Determine Whether Two Date Ranges Overlap
select salaries.emp_no, titles.title, salaries.salary, salaries.from_date
from titles
inner join salaries
on salaries.emp_no = titles.emp_no
AND salaries.from_date <= titles.to_date
AND salaries.to_date >= titles.from_date
where salaries.emp_no=10017;
编辑:可能只需包含检查即可完成工作
AND salaries.from_date >= titles.from_date
AND salaries.to_date < titles.to_date
关于mysql - 连接 2 个 MySQL 表的多个值，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/47018617/