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Without knowing the precise relationships between your entities it is impossible to say whether it is correct or not. Also without knowing what processes you require and what you expect to produce from the data there is no way of knowing if it is fit for purpose. The best I can do it to say it looks reasonable.

@Barand, This is an explanaiton about my relationships

 

I am going to use this database for an institute. In the institute bassically admin can add lectures. To add lectures admin need to login to the system. 

 

To register particular lecture admin need  : lecture name, address1, address2, contact no (mobile, home), subject category, subject, lecturing medium and classes who is conducting.

 

one lecture can conduct many classes. A particular class should have -

  • class type - Eg: Grade 09, Grade 10 etc..
  • class date -
  • class start time -
  • class end time -

Sometimes a lecture may use more than one medium in their lecturing. Eg: English, Japanese, Chinese etc..

 

Every subject shoud partian to one category. Thats why I have used "category", "subject" and "category_subject" tables.

 

A lecture can teach only one subject.

 

Students and parents also can log into the system. Thays why I have added "login_type" in login table.

 

Any I have decided to keep all contact detials in one table. All mean (Lectutes', students' and parents')

 

To contact table I will ask - address1, address2, city, email, mobile, home phone, web url etc...

Edited by thara

I concur with Barand. We would have to have a deep understanding of the structure and process to give good advice. But, here are some comments/questions

 

 

Why does the lecture table have fields for First Name & Last Name? Wouldn't the lectures be associated with a user or contact record? I would think (guess) the user/contact records should have the name values and the lectures table would just have a foreign key reference to that record.

 

 

 

A lecture can teach only one subject

Then why is there a child table "lecture_subject_category"? Can't those fields be included in the lectures table?

 

 

 

Every subject shoud partian to one category

Can the subject-category combinations be different for each lecture? I.e. Is Subject A always in Category B? Or can Subject A be associated to different Catregories in different lectures. If the former is true, then the Subject/Category association should be defined in a separate table and you would only need to include the subject ID in the lectures table.

Psycho, I think the "lecutures" table in the diagram is the "lecturer" table

 

Good catch. If that's the case then the table is named incorrectly.

 

lectures: this is plural form for lecture (i.e. a verbal lesson)

 

lecturers: this is the plural form for a lecturer (i.e a PERSON that performs a lecture)

 

 

 

EDIT: I just looked at the table names again and I thought I had misread it due to it being in French or another language. But, it looks like the spelling is just wrong in multiple places - not even consistently incorrect?!

 

lecutures: should be lecturers

lecuter_medium: should be lecture_medium

lecture_subject_category: This one is right

 

As for field names:

lecture_id: Used in three places. It is spelled correctly, but should really be lecturer_id

lecuture_id: Used in the "lecuter_medium" table.

Edited by Psycho

First of all, I would like to apologize you for my broken english and spelling mistake.

 

 

Then why is there a child table "lecture_subject_category"? Can't those fields be included in the lectures table?

 

Psycho, Yes now I understood that the table of "lecture_subject_category" is not necessary to have. Barand also having got rid of it from his modified version of this design. Thank you for pointed it out me.

 

Barand, You have removed "category_subject" table from your design. So just assume if same subject have in defferent category. Then what happen? then the "subject" table becomes redundant, isn't it? is not it problem? (Here I mean one subject may have under many categroies.)

 

and "user" or "login"?

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