Select-Box (Please see the picture in the details)
lazarus / 16-Databases

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anis2505 · 2014-12-20 13:04

Hi all,

long time  

So I need to make a select-box ( PLZ take a look to The attached
Picture )

It uses 2 TDBListBox.

it's a many to many relationship

Student 1..* <----------------------> 0..* Course

So the list will contain the courses that a student has taken

Any Idea how to make such thing.


regards
G.Anis

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anis2505 · 2014-12-20 16:15

Please, Tell me how you manage many to many relationship,
Tell me how you do such thing not necessary using Select-Boxes.

Thank you all

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engkin · 2014-12-20 17:04

Three tables: tblStudents, tblCourses, and tblStudentCourse.
Example:
tblStudents
ID  Name  Etc...
1   S1
2   S2
...
n  Sn

tblCourses
ID  Name  Etc...
1   C1
2   C2
...
m  Cm

When Student Sx takes a course Cy, add an entry in tblStudentCourse:
ID  SID  CID  Etc....
z    Sx    Cy

As I see it, it is one to many relation

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anis2505 · 2014-12-20 17:26

Hi, Thanks for reply

My problem isn't database design. it's about gui design I want to add
the appropriate course for a student when entering the student main
information

I mean

<form>
<Main Student Information />
</Student Courses />
</form>

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goodname · 2014-12-20 17:48

If your dealing with one student or one course at a time then design
two one to many screens.

Had a case once where I was adding many people to many groups in one
step. The GUI had two multi-select list boxes with the items to be
linked in each box selected.

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engkin · 2014-12-20 17:57

If the concept you have in your image is good enough, then replace
TDBListBox with TListBox and build the logic in code.

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anis2505 · 2014-12-20 18:18

I guess I will do as you sad.
Thank you

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marcov · 2014-12-20 18:50

Your relation is  many to many, but the dialog is not that is one to
many.

I think it might even behave good enough to use master-detail
relations prepared in data sets. Search for "lazarus master detail" or
so.