How to design DataBase Schema for given problem

Question

1.00/5 (1 vote)

See more:

QUE:- A world have multiple forest, forest has multiple trees, and trees has different type of leafs and multiple leafs. Design DB Schema of this structure in fetch the all leafs where forestID=10??
(Hint: use join)
Plzzz help me...

Posted 27-Jan-12 23:01pm

ssoni346

Add a Solution

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Accepted Answer · 2012-01-27T23:07:00

This has the familiar odour of homework - so no code, just suggestions.

What information do you need to store? Look at the objects you have, and list out what objects they are part of, or related to. Draw yourself a picture if you need to.

Then look at how you store all that, with the various relationships, without duplicating information at any time.

Then look at what Join does.

For example, a Tree may have many Leaf objects, but a particular Leaf (as in "this leaf here in my hand") will only be associated with a single Tree - it can't grow on two at the same time! So you will probably want to have a Tree table, and a Leaf table each row of which refers to a specific row in the Tree table.

Sander Rossel · Accepted Answer · 2012-01-27T23:09:00

Solution 2

Hint: Make your own homework... If we do it for you you won't learn anything from it, you might get a job and we'll have to work with people like you who can't solve their own problems.
Worst case scenario: If we answer your question now we might have to work with your code/database in 10 years...

I suggest reading your study books and make something out of it. If your design is flawed your teacher should be able to point out where and why it is faulted. Then you will have learned!
If you have a specific problem like "I have solution A and B, these are the pro's and cons to both what are you opinions?" I think you'll find people here more than willing to help.

Good luck!

Posted 27-Jan-12 23:09pm

Sander Rossel

Comments

ssoni346 28-Jan-12 5:27am

Sorry sir
i was try my best but i have no good knowledge about database and i am fresher and i am looking for a job its a good interview question i want to check that the schema which is made by me for this query is right or wrong so that's why am asking..

Sander Rossel 28-Jan-12 5:38am

You are looking for a job in a field you have no clue about? Seems odd...
Anyway, if you want some help here it's best to show us what you have already tried and tell us where you're stuck. Not present us a problem and suppose we fix it for you.

ssoni346 28-Jan-12 6:48am

firstly i create 3 table 1st is forest(F_id,F_Name), 2nd is Trees(T_ID,T_Name,F_id) and third is leafs(L_id,L_name,T_ID)
query is
select * from leaves where L_ID in (select L_ID from Trees where F_id = 10);

Sander Rossel 28-Jan-12 7:23am

Please use the "Improve question" button on the lower right side of your question. This way other people can read this too and you will get a better chance of getting your question answered. What exactly is your problem? I'd say your tables look about correct. Can't say for certain for your query. I'm sure other people could help in that respect.

Jörgen Andersson 29-Jan-12 16:38pm

You've missed the fact that the leaves were supposed to have different types, so you need to add a field for that purpose.
Otherwise your tables seem fine.
But your query doesn't look so good: the table Trees doesn't have a field L_ID