Foreign Key constraint check

[eluser]Jagar[/eluser]
Let me make an example:

Table
[Students]
student_name varchar
FK_program_id int

table [Program]
Program_id int
Program_name varchar

Now...

[Program]
Program_id Program_Name
1 Software Engineering
2 Networking
3 Web Design

[Student]
Student_name FK_program_id
John 1
James 3
Adam 2

Now right now if I go and delete the program_id 2, CI will throw an error and saying database error, and saying that you cannot delete that id because it's a foreign key of another table.

How can I detect such error, so I can tell the user instead of CI database error.

Thanks