Normalization is the process of organizing columns into tables within a relational database in such a way as to minimize redundancy and avoid insertion, update and deletion anomalies.

learn more… | top users | synonyms

0
votes
0answers
23 views

Normalizing a database [on hold]

I have been developing a social network . I am in the part of normalizing the database.. All I need is to know what transitive dependency really means. Most sources do not explain it as well as they ...
0
votes
0answers
21 views

Schema Design for multiple many-to-one relationships. of which exactly one should exist

Say I have table A, B, and C. B and C can both be related to multiple A's, but each A should have exactly one of either B or C related to it. Which database design is better: A: a_id, b_id NULL, ...
0
votes
1answer
27 views

Relation in 2NF with a transitive dependency?

Tomorrow I have my final exam of Database Design but I have a doubt about the Second Normal Form (2NF). The definition says a relation is in 2NF if no non-prime attribute is partially dependent on a ...
3
votes
2answers
87 views

Survey Database - Respondent Table (1NF or 3NF - Pros and Cons)

Building out a Survey ERD ODS layer. Now i'm debating on the design for my Respondent Table. Not sure if its best to have it as 1NF or 3NF. FOr a quick back story I get a survey extract with ...
0
votes
1answer
79 views

How to remove data redundancy in product table if multiple suppliers are there for same product

I am designing a database where I have different products and suppliers. For example, I have a product, "mobile phone", say an Apple 5S. This will be sold through my website from different suppliers ...
1
vote
1answer
23 views

How would you normalize a database that has multiple products to a single transaction ID?

How would you normalize this? I can't find a way to keep multiple products under a single SalesID
0
votes
1answer
33 views

Database design for actions on some entity

I am making a todo list kind of a service. One todo list will have several items , that can be done/deleted/snoozed etc. Users can also add a new item to the list , delete an item etc. I want to ...
0
votes
1answer
20 views

Create new table values based on partial column value - access

I am trying to remove a ton of unnecessary rows in this table. Currently there are 1.3m of them which are all an individual transaction id - with the country and destination assigned for each which ...
1
vote
1answer
26 views

Get one column table when doing localization

I have got only one column for a table when i create two localized tables. Code as bellow. -- Month CREATE TABLE `month` ( `id` INT PRIMARY KEY NOT NULL AUTO_INCREMENT, ); -- Month Localized ...
0
votes
1answer
22 views

If my understanding of BCNF is correct, how did we know that R1 was not in BCNF?

Given that R(ABCDE) AB->C BC->D CD-> E DE->A Since, B is the only attribute absent on the right-hand side, we would start with B. {B}+ = B . Not a CK. Next, we ...
0
votes
1answer
20 views

What should be the rule for excluding an FD from consideration while doing BCNF or any other Normalization?

Let us consider this example: http://www.mathcs.emory.edu/~cheung/Courses/377/Syllabus/9-NormalForms/examples.html At the first decomposition step, it is using A -> B C D E. On the next step, ...
2
votes
2answers
57 views

What are the prime and non-prime attributes in this relation?

R(HIJKLMNO) L -> MNO HI -> JKLMNO J -> KL K -> H HI is a key. So, H is a prime attribute. But, H is also in non-key part. What are the prime and non-prime attributes in this ...
1
vote
0answers
28 views

Design improvement on multiple references

Im having some 'perception' problem, maybe... I got this table linked multiple times with another small table and maybe is more of a personal problem with the way it looks but I feel there might be a ...
2
votes
0answers
22 views

Creating UNF for multiple actions

I am creating a database design for manufacture company for my coursework. The database design should be able to do these tasks: Buy items from suppliers. (M - N) Items are used for making products. ...
3
votes
2answers
69 views

Should I normalise this database?

I have two database designs thought of for storing messages(instant messages) between users. It will be a group chat system. I have two table designs in mind. One is this: CREATE TABLE ...
0
votes
0answers
45 views

Database Design for group chat

I am creating a chat system as a RESTful API. This is what my design looks so far A request can be made to fetch the newest 50 messages that are part of a group id. Even if I do get a list of ...
2
votes
1answer
126 views

What would be the Candidate key (s) of this relation?

R(ABCDEPG) F={AB->CD, DE->P, C->E, P->C, B->G} To my consideration, the candidate keys are: AB, AG, CD, DE. Am I correct? Why or why not?
0
votes
2answers
51 views

Normal form definitions

I've had trouble finding a straight definition of normal forms online. I don't want any examples or metaphors, just what each form is defined by in a nice format ! I believe there is more than 4 ...
3
votes
2answers
72 views

Database normalization: Which is the best fit?

I have 3 different types of data set: Notification: start_date end_date notification_type country_id state_id Campaign: start_date end_date user_notification Transaction email ...
0
votes
1answer
27 views

Help with some references [closed]

Kind help if anyone has detailed of what a amstrong database are and how are they useful any current important changes in this field or advice on where I may get info in which forum any link
3
votes
1answer
59 views

Entity Relationship Design; The best scenario

TLDR; What would be the best design choice for the scenario below and how would each design react at extremely large data volume? I have experience working with large government database systems ...
0
votes
0answers
36 views

Is this pattern named and how to normalize it?

I am given a data table : State ( StateId, StateNme, StateCounty1, Statecounty1Seat, StateCounty1Rep, StateCounty2, StateCounty2Seat, StateCounty2Rep, StateCounty3,...... ) ...
2
votes
1answer
33 views

This database has two foreign keys going to a single field, is it in 3NF?

Firstly, here is a picture of the database diagram generated by SQL Power Architect. I needed to create a user_id pair in order to match friend requests to users, but this has given me two foreign ...
1
vote
1answer
26 views

Struggling to design addresses table for fast querying

I have two tables: addresses and locations. Locations zipcode city county state Addresses line1 line2 city county state zipcode Posts Id Address_id Body All my users are required to provide at ...
1
vote
0answers
21 views

General Definition of/for Primary Key for Table with Repeated Entries (i.e., not in 1NF)

my first post, my apologies if this does not belong here, please refer me to the/a right site. So I am looking for a general form for a primary key given a table containing non-atomic repeated ...
1
vote
1answer
37 views

Apply Definition of MVD (multivalued dependency) to Example?

Supposedly this multivalued dependency (MVD) and this functional dependency (FD): {W} ↠ {N,D} and {W} → {N} hold in this table: V W N D ================= | v | w | n | 1 | ...
3
votes
1answer
97 views

How can I prove / disprove If A ↠ BC and A → B then A → C

/ From GATE 2007 IT: Consider the following implications relating to functional and multi valued dependencies given below, which may or may not be correct. A) If A ↠ B and A ↠ C then A → BC B) ...
3
votes
1answer
60 views

Does the definition of 2NF prohibit _transitive_ dependencies on a partial key or only direct ones?

We know a relation is in 2NF iff it is in 1NF and no non-prime attribute is dependent on a proper subset of the candidate key. But is "dependent" in this definition strict or loose in the following ...
0
votes
0answers
23 views

ER and Precedence Diagrams

I've been having some difficulties creating a "Cruise Ship" database. Basically, what is known to me: Office has information about: Route (final destination/target) Ships Room Room's class (rank) ...
4
votes
1answer
172 views

Is splitting a CSV column into a separate table(enforcing 1nf) unnecessary complication?

I had very carefully asked the table designer why he had chosen to create CSV columns in multiple tables. The designer's answer was that splitting CSV columns into separate tables was unnecessarily ...
0
votes
1answer
23 views

What adverse effects does a table have when it's not even in 1nf? [closed]

What adverse effects would a table have if it's not even in 1nf ? I googled and read the article on Wikipedia but I couldn't find exactly why a table should be in 1nf. Also, I couldn't find what ...
0
votes
0answers
21 views

Help Normalize Movie Database

I'm creating a small movie database and was wondering if someone can let me know if I'm in the right path: The main entities are movies, people, jobs, trailers, and photos. My main concern is the ...
1
vote
2answers
54 views

SQL Data warehouse and normalization forms

I don't know if it's a simple question but does a data warehouse have different rules when it comes to normalization forms? At the moment I am creating some tables in a data warehouse, and they ...
1
vote
0answers
33 views

is this normalization correct

is this normalization correct for UNF to 3NF
0
votes
0answers
54 views

Hard dba case [schema to store delivery prices for shops]

I want to make a database scheme which would allow me to fetch the delivery price for the different Shops basing on the delivery destination (Address/Region) and order value (price). Here is the ...
5
votes
4answers
271 views

Is it possible to get rid of so-called 'Spurious Tuples' completely?

Is it possible to get rid of so-called 'Spurious Tuples' completely? For example: In this example from a textbook, there is an original table: I don't see anything wrong with the two projections ...
1
vote
0answers
24 views

PostgreSQL: labels vs columns

I have a data structure similar to this: date foo bar baz boo ---------------------------------------- 2015-11-18 1 null 2.5 81.0 2015-11-19 1 78.4 12.8 ...
0
votes
0answers
38 views

How to map this ER model to actual tables?

Suppose we have an ER-design problem like this: A pharmaceutical company sells its products throughout a country. For the ease of sales, the entire country is divided into some Areas. Areas have ...
1
vote
1answer
41 views

Need help on database design

I have a huge database of library system but I have a problem on how to design tables on this database. This is because I have under one entity (for example AUTHOR) a lot of repeatable fields. So I ...
0
votes
1answer
57 views

Normalization from UNF to 3NF

I keep getting confused trying to normalize this data. A company makes and sells a product online. There are ten types of Products, each having a code and price. Their Sales Order department takes ...
0
votes
1answer
21 views

Should i separate ContactInfo (sub-entity) from MyTable (main-entity) or Not?

I am designing a database of a school management system. I have one to one relationship of MyTable with ContactInfo table. I am confused whether I separate contactinfo from MyTable or not. ContactInfo ...
1
vote
0answers
21 views

DATE - Normalization, a multiple ranged query, multiple inserts and multiple update

I have a booking system, airbnb style. TABLES -> prices, house, available_date A house has available days and not available days, but sometimes the days have different prices. A weekend is more ...
0
votes
0answers
42 views

Exam question about BCNF

I am trying to unravel the following question about BCNF from a past exam paper that is available online. The question, which is on page 7 of the linked PDF, says: Suppose that R(A,B,C,D) is a ...
1
vote
0answers
29 views

Understanding Normalisation [closed]

I have a test coming up regarding the 1,2,3 and BCNF Normalisation. The biggest problem understanding I have is from how to convert from 3 -> BCNF. Firstly how to know if the tables are already in 3NF ...
3
votes
2answers
137 views

Is this in 1NF?

I'm an A-level Computer Science student, and my teacher can't explain how to get me from UNF to 1NF. I've researched a little, but I'm not sure as to whether this table (below) is in 1NF or not. I've ...
1
vote
1answer
36 views

How to satisfy 2NF and what are superkeys? - Understanding the algorithm for database normalization in general

Given the table: Student_subject(studentid, subjectid, username, grade) Primary key consisting of a combination of: studentid, subjectid Candidate key consisting of a combination of: ...
0
votes
0answers
43 views

How much normalization is too much

I am working on designing a database for a site I am trying to build, I created what I believe to be the best normalization strategy, to limit the size of particular tables, and the number of tables ...
0
votes
0answers
23 views

Finding the closure of functional dependencies?

I am working on a problem in which I have to look at the relation R with schema R(w, x, y, z), and the three functional dependencies: w -> z ; x,y -> w ;z -> y For every non-empty subset X of the set ...
1
vote
1answer
48 views

How is every binary relation BCNF?

So, as part of my assignment, I have to prove that any relation with two attributes is in BCNF. As per my understanding, if for a relation we have 3rd normal form and one non key attribute ...
1
vote
1answer
40 views

Is it recommend to create a table for addresses? [closed]

I have a table persons with the columns per_id, per_passport, per_name and per_address. Two or more persons can live in the same address (like families or room-mates) so if this happened, the data is ...