DaniWeb IT Discussion Community - Database Design

Looking for On-line Database Hosting

gsdeena — Mon, 06 Oct 2008 14:39:41 GMT

Hello everyone,
My company is looking to find a place to host a landing page. We need this landing page to collect some pretty basic information for us and store it in a database. The techies at our company are currently occupied with other projects, so I have been sent to find some place where for a small fee, we can store our database online and create a fairly simple landing page, preferably with some kind of WYSIWYG editor, that will allow for customizable fields. Anyone know if such a thing is out there, and if so, where?
Thanks a lot,
Deena at GlobalSpec

Division Operation in realtion algebra

helixneu — Sat, 04 Oct 2008 07:47:27 GMT

Find all customers who have an account at all branches located in Brooklyn city.

can ny one tell me how to write this Query .....using Division operator

Relation Schema :
depositor_schema ( customer_name, account_num);
account_schema( account_num, branch_name,balance);

Please try to explain the use of the Division Operation in lucid way ......Since i m new To DB

Hotel Reservation System - Help me on Designing an ER

bk1985 — Wed, 24 Sep 2008 02:59:28 GMT

Please help me on designing an ER for the following scenarios..

* Guest do a hotel reservation
* Handling the billing part for the activities that the guest does during his\her stay @the hotel

Your help will be greatly appreciated, if anyone can help me...

Database Design Help

ashamsa — Sat, 20 Sep 2008 08:39:55 GMT

We are working on an application that caters to a group of institutes. With the current database architecture each institute has its own database, with the same structure but data is different. But there has to be a common database that has some data which need not be repeated in each database, like the vehicles owned by the management etc.
But this vehicle may need to be listed or assigned in each institute's database.
We are a group og beginnerss new to this kind of scenario and strucutre.
We would really appreciate if you can be any assistance in solving or implementing this.

Our issue right now is we can list all vehicles from the common database and assign or use that in each individual database.What will happen if someone deletes the data from the common database? How do we check if this data is used in any of the other databases. This kind of situation may arise in future with other entities also other than vehicles. How do we go further? pls help.

regards
ashamsa

need help e-r diagram

nano99r — Fri, 19 Sep 2008 04:23:27 GMT

I need to create a er diagram which is a entity relationship diagram about a hospital. My professor gave us a case study and the data requirements are wards, staff, patients, patient's next-of-kin, local doctors, patient appointment, out-patients, in-patients, patient medication, surgical and non surgical supplies, pharmaceutical supplies, ward requisitions, and suppliers. I don't know how to design it or even where to start. can someone please help me???

Help to Convert entity-relationship model into a relational database design.

choc.ohloic — Fri, 19 Sep 2008 03:01:58 GMT

I have an ER model which i need to convert into a relational database design.

Can someone please let me know if i am on the right track?

Also how do i represent a foriegn Key, do i use italics, and for prinary key underline?

I have attached the ER model, and please see below as to what i have so far.

CUSTOMERS(Customer_ID,Customer_Name,Biling_Street, Billing_City,Billing_State, Billing_Postcode,Customer_Home_Phone, Customer_Work_Phone, Customer_Mobile_Phone; Faxnbr)

JOBS(Customer_ID,Job_ID,Job_Description, Expected_Start_Date,Expected_Duration_Days, Actual_Start_Date, Actual_Finish_Date, Total_Hours, Total_Litres_Used, Total_Amount_Due, Completed)

INVOICE(Invoice_ID, Job_ID,Invoice_Date,Invoice_Amount, Due_Date)

PAYMENT(Invoice_ID, Payment_ID, Payment_Date,Payment_Amount)

EMPLOYEE(Employee_ID, Employee_Name,Street, City, State, Postcode, Employee_Home_Phone, Employee_Mobile_Phone, Tax_File_Nbr)

TIMESHEET(Employee_ID, Job_ID, Timesheet_ID, Start_Time_Stamp, Finish_Time_Stamp, Hours_Worked, Litres_Used)

Thanks for your help and yes this is an assignment, so all guidence and reasoning behind suggsestion would be appreciated.

Attached Files

ERMODEL.doc (67.0 KB)

e-r diagram

rain2shine — Thu, 18 Sep 2008 13:47:02 GMT

Hi, I need help bad, im trying to make an E-R diagram from the following:

The City House Service (CHS) is an onoprofit service that advocates the development and inprovement of low-income housing. The CHS operates in a metropolitan area of approx. 2.2 million people in a mid-west city.

The CHS maintains data about the location, availability, and condition of low-income housing in 22 different census tracts in the metro. area. Within the boundaries of these tracts are approx. 250 different buildings that provide low-income housing. On average, each building contains 25 apartments or other units.

The CHS keeps data about each Census tract, including geographical boundaries, median income of population, elected officials, pronciple business, principle investors involved in attributes in that tract, and other dempgraphic and economic data. It also maintains a limited amout of data about crime. For each building, the CHS stores the name, address, size, owner(s) name and address, mortgagor(s) name and address, renovations and repairs, and availability of facilities for handicapped people. In addition, the CHS keeps a list of each of the units within each building, including the type of unit, size, number of bedrooms, number of baths, kitchen and dining facilities, location in the building, and any special remarks. The CHS would like to maintain data regarding the average occupancy rates for each unit, but to date, it has been unable to collect or store such data. The CHS does, however, keep data about whether a given units is occupied.

The CHS serves as an information clearinghous and offers 3 basic services. First, it works with politicians, lobbyists, and advocacy groups to support legislation that encourages the development of low-income housing through tax incentives, developmental zoning perferences, and other legislative inducements. To accomplish this, the CHS provdes inforation about low-income housing to state, county, and city governents. Second, through speeches, seminars, displays at convenctions, and other public relations activites, the CHS officials strive to raise the community's consciousness about the need for low-income housing. Finally, the CHS provides information about the avaiability of low-income housing to other agencies that work with the low-income and homeless population.

You need to do the following work:
1. Developing an E-R diagram for a database to support the the tracking needs of the CHS, including possible weak entities within this data model
2. Specifying tables and their promary keys and foreign keys.
3. Describing how you have represented weak entities in those tables.

The only tables taht i know of are: Building, Mortgagors, Unit(s) Census government and census tract. My teacher said there would be a minmum of 7 tables and i believe owner would be one.

If anyone could give me any guidance on this, it would be greatly apprciated.

Regarding ASCII data type

srs_grp — Thu, 18 Sep 2008 09:40:34 GMT

Does SQL support ASCII data type?Or we need to do some type casting for it.?

Database Design for Dating Site

mjuni — Thu, 18 Sep 2008 03:17:41 GMT

I am tasked with designing a dating site in asp.net with VB using sql server 2005 as the database platform. I have not had a lot of advanced database design experience so I am hoping someone can help me out with this one....

For each user there is a profile (some profile questions might be: nationality, education, age, eye color, etc, etc..). Each of these profile questions could either contain a single value from a radio button (example: are you male or female), multiple values from a list of checkboxes (example: check your hobbies and interests) or text (ex: tell in a short paragraph what you are looking for).

Does anyone have any advice as to the best way to design this. Here are some of the options I am considering:

1) Create a different table for each profile question:
example:

EyeColor
--------
UserId (int or guid)
EyeColor (varchar)

Interests
---------
UserId
InterestValue

I see this as being a problem because there could be upwards of 50 table joins for each search query and the database would need to be updated if a profile question is added or no longer used.

2) Put the entire profile in one table:
example:

Profile
-------
UserId (int or guid)
HairColor (varchar)
EyeColor (varchar)
LikesMovies (bit)
LikesHiking (bit)

I see this a being a problem as this table could contain up to 70 columns and I think serially searching through this one gigantic table could be very slow if the user base gets large. Also as with the above scenario, the DB would need to be changed to accomidate any additions/deletions to the profile questions.

3) Ideally I would like to design a flexible structure to allow questions of different types (radio, check box, text box) to be added/deleted from an admin interface without having to modify the db structure but I don't know how to design this so it would be efficient for searches.

Another dilema is that I would like to avoid using dynamic SQL, but I dont know how I could search accross a varied number of parameters with a stored procedure.

Could anyone give me some advice on any of the above.

Any advice would be appreciated. Thanks.

Database design question

RockabillyJim — Tue, 16 Sep 2008 23:40:48 GMT

I have two tables with foreign keys to the same parent table and a junction table between them to map a many to many relationship. I want to know how best to enforce data integrity in the junction table so that both parents' parent is the same.

Example:

CREATE TABLE Parent

(

ParentCode char(3) NOT NULL,

Name varchar(50) NOT NULL,

PRIMARY KEY (ParentCode)

);



CREATE TABLE Child1

(

Child1Code char(3) NOT NULL,

Name varchar(50) NOT NULL,

ParentCode char(3) REFERENCES Parent(ParentCode)

PRIMARY KEY (Child1Code)

);



CREATE TABLE Child2

(

Child2Code char(3) NOT NULL,

Name varchar(50) NOT NULL,

ParentCode char(3) REFERENCES Parent(ParentCode)

PRIMARY KEY (Child1Code)

);



CREATE TABLE ChildJunction

(

Child1Code char(3) NOT NULL,

Child2Code char(3) NOT NULL,

Attribute int NOT NULL,

PRIMARY KEY (Child1Code, Child2Code)

);

How do I ensure that the Child1 and Child2 in ChildJunction have the same Parent?

The best I have so far is that ChildJunction includes a ParentCode column, I create a UNIQUE constraint on Child1Code + ParentCode in Child1 and a UNIQUE constraint on Child2Code + ParentCode in Child2 and the FOREIGN KEYS from ChildJunction are ChildJunction.Child1Code = Child1.Child1Code AND ChildJunction.ParentCode = Child1.ParentCode and ChildJunction.Child2Code = Child2.Child2Code AND ChildJunction.ParentCode = Child2.ParenCode.

But that leaves me with redundant data in ChildJunction (i.e. ParentCode).

Am I missing something? This must be a common problem? have I designed the Child tables wrong? Or the Parent table?

Any help gratefully received...

Thanks,
Simon

Urgent UML Help

arkabus — Sun, 14 Sep 2008 15:28:46 GMT

I desperately need help with this database stuff as I have no clue what to do or where to begin.

Business Description
Red Rocket Deliveries has a fleet of vehicles which costs them a lot of money to run and maintain. Most of relevant information is currently recorded, but it can not be effectively analysed, because it is scattered amongst various paper and computer based systems. In order to better understand and manage this expense, Red Rocket intends to establish a database. The business operates several different kinds of vehicle, including motorcycles, vans and trucks. The expected lifecycle of a vehicle depends on its make and model. Each make and model has an expected fuel consumption, number of kilometres between services, average service cost, purchase price, expected disposal revenue and maximum years or kilometres of service. This information is used to predict expenses. Actual expenditures are also be recorded. Each fuel purchase is associated with a particular vehicle. Each vehicle service is recorded, and at the end of each week, the odometer reading of each vehicle is recorded.

Requirements
Essential
1. How much did we spend on fuel last week?
2. List all purchases of fuel that exceed the capacity of the vehicle for which it was purchased.
3. Which vehicles are due for service?
4. How much would it cost to replace all of our motorcycles with Harley-Davidson Sportsters?

Desirable
1. Which vehicles are consuming at least 20% more fuel than estimated?
2. List the average price of fuel by the day of the week on which it was purchased.
3. Which vehicles will be due for service at the end of next week, assuming they travel the same number of kilometres as last week?
4. For each make and model of vehicle, give the average cost of parts in the first year of service and in the last year of service.
5. Which motorcycles will reach the end of their service life in the next 6 months, assuming they continue their average weekly mileage?

Deliverables
We require a small demonstration database and queries which provide the information
listed above. Specifically, we require:
1. A UML class diagram modelling the required data. The main model
elements should be defined and explained in the submission text.
2. SQL code to create a database schema corresponding to the class diagram.
(createSchema.sql)
3. SQL code to populate the database with test data that adequately demonstrates
the required queries. (populate.sql)
4. SQL queries to provide each item of information listed in the system requirements.
(queries.sql)

Normalization question??

GrimJack — Sat, 13 Sep 2008 03:08:47 GMT

Is there an algorithm for normalizing data? I think I understand the process but how do I know when I have drilled down to the bottom?

Need a opinion/advice about university students enrollement system db pls HELP

roxys — Fri, 12 Sep 2008 14:24:05 GMT

Hello,

I was wondering if someone could help me a bit here. Im trying to
desing an electronic university students enrollement system.

The system requirements are as follows:
1.Students can enroll themself for 1 or more courses. And a course can be taken from 1 or more students.
2. There are 2 levels of courses. Level 1 is a course of 1 day and level 2 is a course of 5 days.
3. The students will be divided in groups. So 1 students can be in 1 or more groups and a group can consist of 1 or more students.
4. Teacher can teach 1 or more courses but a course can only be given by 1 teacher.
5. The course will end with an exam.
6. The students can take the exam only if they attend to the minimum required days of the course. If a student is taken a level 1 course, they must attend 1 day to the course. If a student is taken a level 2 course, they must minimum attend 3 days of the course.
7. Students that passed the exam must receive an diploma.

The relationships between student and course is a many to many relationship, so i introduced a table between them that i called course enrollment that have as PK student_id and course_id.

The relationship between student and group I also introduced a table between them that I called StudentsGroup and I set student_id and group_id as PK.

The relationship between Group and Course I have it as a 1 to many relationship, because 1 course can be given to many groups, ( example the course Basic of Accounting can be given to Group A and Group B) But in a group can only 1 course be given. (example in Group A can only Research be given)

The relationship between teacher and course i have as 1 to many.

And I have a entity named Level that has as attributes level_id and level_description that is attached to the attribute level_id in the course entity/table.

Now I don't know where do I have to put the attendance issue and the level requirements issue to fit in the erd.

Could someone PLEASE HELP ME with this erd.

Attached Images

erd.JPG (74.2 KB)

question

msundastud — Tue, 09 Sep 2008 14:38:03 GMT

trying to create a 3NF database given a classic car database with members name, contact info and car.

need to know stuff....

members have more than one car
more than one member can have the same car
be able to find the club member of each car
able to find car of each member
include necessary and primary keys
must be able to select a model car and find all members who have that car

What are the advantages of having three-level database architecture

Azher — Tue, 09 Sep 2008 00:21:53 GMT

Hello all i want to know that why we are using three level architecture ? What are the advantages of having three-level database architecture? How are they related to Data Independence? please Explain with the help of an example.

Thanks