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• Is data integrity possible without normalization?

  - by shuniar

  I am working on an application that requires the storage of location information such as city, state, zip code, latitude, and longitude. I would like to ensure: Location data is accurate Detroit, CA Detroit IS NOT in California Detroit, MI Detroit IS in Michigan Cities and states are spelled correctly California not Calefornia Detroit not Detriot Cities and states are named consistently Valid: CA Detroit Invalid: Cali california DET d-town The D Also, since city/zip data is not guaranteed to be static, updating this data in a normalized fashion could be difficult, whereas it could be implemented as a de facto location if it is denormalized. A couple thoughts that come to mind: A collection of reference tables that store a list of all states and the most common cities and zip codes that can grow over time. It would search the database for an exact or similar match and recommend corrections. Use some sort of service to validate the location data before it is stored in the database. Is it possible to fulfill these requirements without normalization, and if so, should I denormalize this data?

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• Does semi-normalization exist as a concept? Is it "normalized"?

  - by Gracchus

  If you don't mind, a tldr on my experience: My experience tldr I have an application that's heavily dependent upon uncertainty, a bane to database design. I tried to normalize it as best as I could according to the capabilities of my database of choice, but a "simple" query took 50ms to read. Nosql appeals to me, but I can't trust myself with it, and besides, normalization has cut down my debugging time immensely over and over. Instead of 100% normalization, I made semi-redundant 1:1 tables with very wide primary keys and equivalent foreign keys. Read times dropped to a few ms, and write times barely degraded. The semi-normalized point Given this reality, that anyone who's tried to rely upon views of fully normalized data is aware of, is this concept codified? Is it as simple as having wide unique and foreign keys, or are there any hidden secrets to this technique? Or is uncertainty merely a special case that has extremely limited application and can be left on the ash heap?

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• Normalization in plain English

  - by Yada

  I sort of understand the concept of database normalization but always have a hard time explaining it in plain English especially for a job interview. I have read the wikipedia post, but still find it hard to explain the concept to none developers. "Design a database in a way not to get duplicated data" is the first thing that comes to mind. Does anyone was a nice way to explain the concept of database normalization in plain English. And what are some nice examples to show the differences between first, second and third normal forms. Say you go to a job interview and the person asks: Explain the concept of normalization and how would go about designing a normalized database. What key points are the interviewer looking for?

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• Why many designs ignore normalization in RDBMS?

  - by Yosi

  I got to see many designs that normalization wasn't the first consideration in decision making phase. In many cases those designs included more than 30 columns, and the main approach was "to put everything in the same place" According to what I remember normalization is one of the first, most important things, so why is it dropped so easily sometimes? Edit: Is it true that good architects and experts choose a denormalized design while non-experienced developers choose the opposite? What are the arguments against starting your design with normalization in mind?

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• mySQL and general database normalization question

  - by Sinan

  I have question about normalization. Suppose I have an applications dealing with songs. First I thought about doing like this: Songs Table: id | song_title | album_id | publisher_id | artist_id Albums Table: id | album_title | etc... Publishers Table: id | publisher_name | etc... Artists Tale: id | artist_name | etc... Then as I think about normalization stuff. I thought I should get rid of "album_id, publisher_id, and artist_id in songs table and put them in intermediate tables like this. Table song_album: song_id, album_id Table song_publisher song_id, publisher_id Table song_artist song_id, artist_id Now I can't decide which is the better way. I'm not an expert on database design so If someone would point out the right direction. It would awesome. Are there any performance issues between two approaches? Thanks

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• Are these tables respect the 3NF Database Normalization?

  - by penas

  AUTHOR table Author_ID, PK First_Name Last_Name TITLES table TITLE_ID, PK NAME Author_ID, FK DOMAIN table DOMAIN_ID, PK NAME TITLE_ID, FK READERS table READER_ID, PK First_Name Last_Name ADDRESS CITY_ID, FK PHONE CITY table CITY_ID, PK NAME BORROWING table BORROWING_ID,pk READER_ID, fk TITLE_ID, fk DATE HISTORY table READER_ID TITLE_ID DATE_OF_BORROWING DATE_OF_RETURNING Are these tables respect the 3NF Database Normalization? What if 2 authors work together for the same title? The column Addresss should have it's own table? When a reader borrows a book, I make an entry in BORROWING table. After he returns the book, I delete that entry and I make another one entry in HISTORY table. Is this a good idea? Do I brake any rule? Should I have instead one single BORROWING table with a DATE_OF_RETURNING column?

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• Arrays in database tables and normalization

  - by Ivan Petrov

  Hi! Is it smart to keep arrays in table columns? More precisely I am thinking of the following schema which to my understanding violates normalization: create table Permissions( GroupID int not null default(-1), CategoryID int not null default(-1), Permissions varchar(max) not null default(''), constraint PK_GroupCategory primary key clustered(GroupID,CategoryID) ); and this: create table Permissions( GroupID int not null default(-1), CategoryID int not null default(-1), PermissionID int not null default(-1), constraint PK_GroupCategory primary key clustered(GroupID,CategoryID) ); UPD: Forgot to mention, in the scope of this concrete question we will consider that the "fetch rows that have permission X" won't be performed, instead all the lookups will be made by GroupID and CategoryID only Thoughts? Thanks in advance!

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• Simple Database normalization question...

  - by user365531

  Hi all, I have a quick question regarding a database that I am designing and making sure it is normalized... I have a customer table, with a primary key of customerId. It has a StatusCode column that has a code which reflects the customers account status ie. 1 = Open, 2 = Closed, 3 = Suspended etc... Now I would like to have another field in the customer table that flags whether the account is allowed to be suspended or not... certain customers will be automatically suspended if they break there trading terms... others not... so the relevant table fields will be as so: Customers (CustomerId(PK):StatusCode:IsSuspensionAllowed) Now both fields are dependent on the primary key as you can not determine the status or whether suspensions are allowed on a particular customer unless you know the specific customer, except of course when the IsSuspensionAllowed field is set to YES, the the customer should never have a StatusCode of 3 (Suspended). It seems from the above table design it is possible for this to happen unless a check contraint is added to my table. I can't see how another table could be added to the relational design to enforce this though as it's only in the case where IsSuspensionAllowed is set to YES and StatusCode is set to 3 when the two have a dependence on each other. So after my long winded explanation my question is this: Is this a normalization problem and I'm not seeing a relational design that will enforce this... or is it actually just a business rule that should be enforced with a check contraint and the table is in fact still normalized. Cheers, Steve

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• mysql database normalization question

  - by Chocho

  here is my 3 tables: table 1 -- stores user information and it has unique data table 2 -- stores place category such as, toronto, ny, london, etc hence this is is also unique table 3 -- has duplicate information. it stores all the places a user have been. the 3 tables are linked or joined by these ids: table 1 has an "table1_id" table 2 has an "table2_id" and "place_name" table 3 has an "table3_id", "table1_id", "place_name" i have an interface where an admin sees all users. beside a user is "edit" button. clicking on that edit button allows you to edit a specific user in a form fields which has a multiple drop down box for "places". if an admin edits a user and add 1 "places" for the user, i insert that information using php. if the admin decides to deselect that 1 "places" do i delete it or mark it as on and off? how about if the admin decides to select 2 "places" for the user; change the first "places" and add an additional "places". will my table just keep growing and will i have just redundant information? thanks.

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• Normalization of database for timesheet tool and ensure data integrity

  - by fireeyedboy

  I'm creating a timesheet application. I have the following entities (amongst others): Company Employee = an employee associated with a company Client = a client associated with a company So far I have the following (abbreviated) database setup: Company - id - name Employee - id - companyId (FK to Company.id) - name Client - id - companyId (FK to Company.id) - name Now, I want an employee to be associated with a client, but only if that client is associated with the company the employee works for. How would you guarantee this data integrity on a database level? Or should I just depend on the application to guarantee this data integrity? I thought about creating a many to many table like this: EmployeeClient - employeeId (FK to Employee.id) - companyId \ (combined FK to Client.companyId, Client.id) - clientId / Thus, when I insert a client for an employee along with the employee's company id, the database should prevent this when the client is not associated with the employee's company id. Does this make sense? Because this still doesn't guarantee the employee is associated with the company. How do you deal with these things? UPDATE The scenario is as followed: A company has multiple employees. Employees will only be linked to one company. A company has multiple clients also. Clients will only be linked to one company. (Company is a sandbox, so to speak). An employee of a company can be linked to a client of it's company, but only if the client is part of the company's clientele. In other words: The application will allow a company to create/add employees and create/add clients (hence the companyId FK in the Employee and Client tables). Next, the company will be allowed to assign certain clients to certain of it's employees (EmployeeClient table). Imagine an employee working on projects for a few clients for which s/he can write billable hours, but the employee must not be allowed to write billable hours for clients they are not assigned to by their employer (the company). So, employees will not automatically have access to all their company's clients, but only to those that the company has selected for them. Hopefully this has shed some more light on the matter.

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• MySQL Normalization stored procedure performance

  - by srkiNZ84

  Hi, I've written a stored procedure in MySQL to take values currently in a table and to "Normalize" them. This means that for each value passed to the stored procedure, it checks whether the value is already in the table. If it is, then it stores the id of that row in a variable. If the value is not in the table, it stores the newly inserted value's id. The stored procedure then takes the id's and inserts them into a table which is equivalent to the original de-normailized table, but this table is fully normalized and consists of mainly foreign keys. My problem with this design is that the stored procedure takes approximately 10ms or so to return, which is too long when you're trying to work through some 10million records. My suspicion is that the performance is to do with the way in which I'm doing the inserts. i.e. INSERT INTO TableA (first_value) VALUES (argument_from_sp) ON DUPLICATE KEY UPDATE id=LAST_INSERT_ID(id); SET @TableAId = LAST_INSERT_ID(); The "ON DUPLICATE KEY UPDATE" is a bit of a hack, due to the fact that on a duplicate key I don't want to update anything but rather just return the id value of the row. If you miss this step though, the LAST_INSERT_ID() function returns the wrong value when you're trying to run the "SET ..." statement. Does anyone know of a better way to do this in MySQL? Thank you

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• The Road to Professional Database Development: Database Normalization

  Not only is the process of normalization valuable for increasing data quality and simplifying the process of modifying data, but it actually makes the database perform much faster. To prove the point, Peter Larsson takes a large unnormalised database and subjects it to successive stages of normalisation. Get smart with SQL Backup ProGet faster, smaller backups with integrated verification.Quickly and easily DBCC CHECKDB your backups. Learn more.

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• How do you normalize one-to-one-or-the-other relationships?

  - by Jekke

  I'm storing data on baseball statistics and would like to do so with three tables: players, battingStats, and pitchingStats. For the purpose of the question, each player will have batting stats or pitching stats, but not both. How would I normalize such a relationship in 3NF?

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• database is normalized but the following is a problem please help

  - by user287745

  but the prob is there are relations ships which are so huge that after normalizing they have like a 20 primary keys( composite keys) which are really foreign keys but have to be declared as primary keys to identify the relationship uniquely. so please help? is it correct and i apologize to the expert community for not accepting answers, i was not aware that accepting is possible, the TICK MARK is that visible :-)

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• Does normalization really hurt performance in high traffic sites?

  - by Luke101

  I am designing a database and I would like to normalize the database. I one query I will joining about 30-40 tables. Will this hurt the website performance if it ever becomes extremely popular? This will be the main query and it will be getting called 50% of the time. The other queries I will be joining about 2 tables. I have a choice right now to normalize or not to normalize but if the normalization becomes a problem in the future i may have to rewrite 40% of the software and it may take me a long time. Does normalization really hurt in this case? Should I denormalize now while I have the time?

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• Vector normalization gives very imprecise results

  - by Kipras

  When I normalize vectors I receive very strange results. The lengths of the normalized vectors range from 1.0 to almost 1.5. The functions are all written by me, but I just can't find a mistake in my algorithm. When I normalize I just divide all components of the vector by the vector's length. public double length(){ return Math.sqrt(x*x + y*y); } public void normalize(){ if(length() > 0){ x /= length(); y /= length(); } } Is this supposed to happen? I mean I can see the length ranging from 0.9 to 1.1 at worst, but this is just overwhelming. Cheers

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• mySQL Efficiency Issue - How to find the right balance of normalization...?

  - by Foo

  I'm fairly new to working with relational databases, but have read a few books and know the basics of good design. I'm facing a design decision, and I'm not sure how to continue. Here's a very over simplified version of what I'm building: People can rate photos 1-5, and I need to display the average votes on the picture while keeping track of the individual votes. For example, 12 people voted 1, 7 people voted 2, etc. etc. The normalization freak of me initially designed the table structure like this: Table pictures id* | picture | userID | Table ratings id* | pictureID | userID | rating With all the foreign key constraints and everything set as they shoudl be. Every time someone rates a picture, I just insert a new record into ratings and be done with it. To find the average rating of a picture, I'd just run something like this: SELECT AVG(rating) FROM ratings WHERE pictureID = '5' GROUP by pictureID Having it setup this way lets me run my fancy statistics to. I can easily find who rated a certain picture a 3, and what not. Now I'm thinking if there's a crapload of ratings (which is very possible in what I'm really designing), finding the average will became very expensive and painful. Using a non-normalized version would seem to be more efficient. e.g.: Table picture id | picture | userID | ratingOne | ratingTwo | ratingThree | ratingFour | ratingFive To calculate the average, I'd just have to select a single row. It seems so much more efficient, but so much more uglier. Can someone point me in the right direction of what to do? My initial research shows that I have to "find the right balance", but how do I go about finding that balance? Any articles or additional reading information would be appreciated as well. Thanks.

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• Quickly switch Win7 volume normalization on/off?

  - by romkyns

  Is there some way to quickly toggle the state of volume normalization in Windows 7? When it's off watching movies late is tricky, and when it's on it messes with music in a bad way. It's a great feature, but argh, it requires me to make my way through so many dialogs... Any solution that requires no more than a couple of clicks or keystrokes is welcome - shortcuts, AutoHotkey, tray icon apps.

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• What stage of normalization is this? (moving repeating data into separate table)

  - by Sergio

  Hi There, I have noticed that when designing a database I tend to shift any repeating sets of data into a separate table. For example, say I had a table of people, with each person living in a state. I would then move these repeating states into a separate table and reference them with foreign keys. However, what if I was not storing any more data about states. I would then have a table with StateID and State in. Is this action correct? State is dependant on the primary key of the users table, so does shifting it into its own table help with anything? Thanks,

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• De-normalization for the sake of reports - Good or Bad?

  - by Travis

  What are the pros/cons of de-normalizing an enterprise application database because it will make writing reports easier? Pro - designing reports in SSRS will probably be "easier" since no joins will be necessary. Con - developing/maintaining the app to handle de-normalized data will become more difficult due to duplication of data and synchronization. Others?

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• what is meant by normalization in huge pointers

  - by wrapperm

  Hi, I have a lot of confusion on understanding the difference between a "far" pointer and "huge" pointer, searched for it all over in google for a solution, couldnot find one. Can any one explain me the difference between the two. Also, what is the exact normalization concept related to huge pointers. Please donot give me the following or any similar answers: "The only difference between a far pointer and a huge pointer is that a huge pointer is normalized by the compiler. A normalized pointer is one that has as much of the address as possible in the segment, meaning that the offset is never larger than 15. A huge pointer is normalized only when pointer arithmetic is performed on it. It is not normalized when an assignment is made. You can cause it to be normalized without changing the value by incrementing and then decrementing it. The offset must be less than 16 because the segment can represent any value greater than or equal to 16 (e.g. Absolute address 0x17 in a normalized form would be 0001:0001. While a far pointer could address the absolute address 0x17 with 0000:0017, this is not a valid huge (normalized) pointer because the offset is greater than 0000F.). Huge pointers can also be incremented and decremented using arithmetic operators, but since they are normalized they will not wrap like far pointers." Here the normalization concept is not very well explained, or may be I'm unable to understand it very well. Can anyone try explaining this concept from a beginners point of view. Thanks, Rahamath

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• On the fly volume normalization (waveform capping) for VLC or OS X

  - by Grammar Nazi

  I'm looking to impose a hard limit on a movie. In particular when I have earbuds in and a reasonable volume set, loud or sudden sounds (gun shot, dramatic sound effects, gun fire, etc) are loud enough to hurt. Lowering the volume makes speech and other sounds hard to hear. Is there a third party on-the-fly solution for this, or a plug-in for VLC that I can use?

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• database----database normalization

  - by runeveryday

  someone told me the following table isn't fit for the second database normalization. but i don't know why? i am a newbie of database design, i have read some tutorials of the 3NF. but to the 2NF and 3NF, i can't understand them well. expect someone can explain it for me. thank you, +------------+-----------+-------------------+ pk pk row +------------+-----------+-------------------+ A B C +------------+-----------+-------------------+ A D C +------------+-----------+-------------------+ A E C +------------+-----------+-------------------+

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• Automatic adaptive gain normalization

  - by Eduardo

  How may I normalize a (voice) audio mp3 or aac file with no loss, having the gain rised as much as possible with little distortion, so in a long conversation people that speak softer can have more gain for their voice and people that speak louder can have less gain?

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• ActiveRecord field normalization

  - by Bill

  I feel bad asking this question, as I thought I knew enough about Activerecord to answer this myslef. But such is the way of having SO available ... I'm trying to remove the commas from a field in a model of mine, I want the user to be able to type a number , ie 10,000 and that number be stored in the database as 10000. I was hoping that I could do some model-side normalization to remove the comma. I don't want to depend on the view or controller to properly format my data. I tried ; before_validation :normalize def normalize self['thenumber'] = self['thenumber'].to_s.gsub(',','') end no worky :(

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