Php 避免从select语句中显示重复的值

我使用foreach循环来获取结果，但是我得到了不必要的重复结果。下面您将看到，我得到的值显示了两次以上。在查询select语句中，我在表之间进行内部联接。然后我执行一个

foreach

循环来显示这些结果。结果显示在三个表格中：academy、courses\u by\u academy和person。它们都共享一个外键academy\u id。我不确定这是查询还是foreach循环的格式。如何显示如下所示的信息而不显示任何重复信息

PHP

当前显示：

-------------------COURSES_OFFERED------------------
Course Name: Biology
Start Date: 2013-11-13
End Date: 2013-11-26
---------------------PERSONEL-----------------------
First Name: Person1
Last Name: Last1
Email: test1@gmail.com
This person has the role of an instructor: 1
This person has the role of a contact: 
Phone: 1234567890
Fax: 1234567890
-------------------COURSES_OFFERED------------------
Course Name: Calculus
Start Date: 2013-11-19
End Date: 2013-11-16
---------------------PERSONEL-----------------------
First Name: Person1
Last Name: Last1
Email: test1@gmail.com
This person has the role of an instructor: 1
This person has the role of a contact: 
Phone: 1234567890
Fax: 1234567890
-------------------COURSES_OFFERED------------------
Course Name: Biology
Start Date: 2013-11-13
End Date: 2013-11-26
---------------------PERSONEL-----------------------
First Name: Person2
Last Name: Last2
Email: test2@gmail.com
This person has the role of an instructor: 0
This person has the role of a contact: 1
Phone: 1234567890
Fax: 1234567890
-------------------COURSES_OFFERED------------------
Course Name: Calculus
Start Date: 2013-11-19
End Date: 2013-11-16
---------------------PERSONEL-----------------------
First Name: Person2
Last Name: Last2
Email: test2@gmail.com
This person has the role of an instructor: 0
This person has the role of a contact: 1
Phone: 1234567890
Fax: 1234567890

表值

---

如果您的意思是防止重复行，可以使用

distinct

短语

select distinct [columns...] 
from ...

---

请注意，

distinct

防止使用指定的列复制行。

为什么说有重复行？图像中显示的四行都不同。它适用于完全相似的行。在您的示例中，这四行是不同的，并且没有重复。如何显示所需的信息（所需的显示方式）？

-------------------COURSES_OFFERED------------------
Course Name: Biology
Start Date: 2013-11-13
End Date: 2013-11-26
---------------------PERSONEL-----------------------
First Name: Person1
Last Name: Last1
Email: test1@gmail.com
This person has the role of an instructor: 1
This person has the role of a contact: 
Phone: 1234567890
Fax: 1234567890
-------------------COURSES_OFFERED------------------
Course Name: Calculus
Start Date: 2013-11-19
End Date: 2013-11-16
---------------------PERSONEL-----------------------
First Name: Person1
Last Name: Last1
Email: test1@gmail.com
This person has the role of an instructor: 1
This person has the role of a contact: 
Phone: 1234567890
Fax: 1234567890
-------------------COURSES_OFFERED------------------
Course Name: Biology
Start Date: 2013-11-13
End Date: 2013-11-26
---------------------PERSONEL-----------------------
First Name: Person2
Last Name: Last2
Email: test2@gmail.com
This person has the role of an instructor: 0
This person has the role of a contact: 1
Phone: 1234567890
Fax: 1234567890
-------------------COURSES_OFFERED------------------
Course Name: Calculus
Start Date: 2013-11-19
End Date: 2013-11-16
---------------------PERSONEL-----------------------
First Name: Person2
Last Name: Last2
Email: test2@gmail.com
This person has the role of an instructor: 0
This person has the role of a contact: 1
Phone: 1234567890
Fax: 1234567890

select distinct [columns...] 
from ...