Database Normalization in SQL - 1NF, 2NF, 3NF, 4NF - SQL Training Online
ฝัง
- เผยแพร่เมื่อ 9 ก.ค. 2024
- Database Normal Forms with Examples.
In this video I show you how to normalize your relational database.
What is covered:
--1st Normal Form and Atomic Values
--2nd Normal Form and Partial Dependence
--3rd Normal Form and Transitive Dependence
--4th Normal Form and Multi-Value Facts
I start with smaller examples for 1NF, 2NF, 3NF, and 4NF. Then I move into a more comprehensive example that uses all of the normal forms together.
TABLE OF CONTENTS
00:00 - Intro
01:07 - 1st Normal Form
4:18 - 2nd Normal Form
9:44 - 3rd Normal Form
13:50 - 4th Normal Form
17:33 - Normalizing Customer Orders
20:35 - Customer Table (2NF)
21:55 - Product Table (2NF)
24:20 - Order Header vs Order Lines
29:05 - Product Table (3NF)
31:25 - Customer Table (1NF, 4NF)
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TABLE OF CONTENTS
00:00 - Intro
01:07 - 1st Normal Form
4:18 - 2nd Normal Form
9:44 - 3rd Normal Form
13:50 - 4th Normal Form
17:33 - Normalizing Customer Orders
20:35 - Customer Table (2NF)
21:55 - Product Table (2NF)
24:20 - Order Header vs Order Lines
29:05 - Product Table (3NF)
31:25 - Customer Table (1NF, 4NF)
nee.
@@Kipviss .
That's brilliant, confused by a textbook but fully normalised now!
This video will top the search results in youtube on "DB Normalization" going forward.
I have been struggling with this concept all week in class. I finally get it. Thank you so much.
Thank you for explaining this so clearly. I like the focus and the delivery.
Great explanation! It's obvious that you actually understand the topic well, and you're not just spewing out definitions. I've had some difficulty understanding these concepts until now
Excellent video and clear explanation. Can't get better than this!
Thanks a lot!
Your explanation is absolutely easy to understand, examples are perfect.
You did a great job teaching a complex topic in an understandable way! Just subscribed to your channel and expect you to get many more in the coming months because you’re producing quality content-it really stands out from the other videos on normalization. Keep up the great work!
Really useful information. Helped me with my concepts. Thank you so much Joey.
Thank you so much, you just make it easy for me to understand, that what a perfect teacher looks like.
Best explaination i have seen so far in any book or video!. Hats off. Great example and walk thourgh
I really like this video. It was so much easier for me to understand normal forms by watching this video instead of reading my book. Thank you so much!
Great, concise video! Thank you
Thank you! This was an excellent format for a visual learner like me!
Simply great!
Great video Joey.
Thanks. Very easy to digest explanation on normalization.
I'm a total noob on this topic and watched many videos about database normalization, this is the simplest explanation on the topic and the one that helped me the most improving my database structure. Thanks a lot!
love this one very much!!!!
Great, thank you!
Thank you so much for this video.
The absolute best !!!! Saving me from the land of total confusion!!!
Thank you so much , this helped me a lot , keep it up plz
Thank you so much. your video is really useful for me
Joey, Thank you so much for helping us the little guys.
awesome video. Great explanation.
excellent work Joey
I cannot thank you enough.
Great! Thanx!
You're a great teacher - thanks for making this available to everyone.
Thank you a lot, you are different!
Great explanation of the topic. Thank you for teaching us :)
Thanks for this video
Brilliant ,,,,,lecturer
Very well explained
Extremely helpful! Thank you Joey!!!
Thank you! the best explanation I have found on the net!!
Excellent job
This is good. I'm new to this therefore, I'll need a week to design my first database...lol
Thanks for this
That was Excellent ! I guess I’ve been lucky with not having so complicated data. Thanks, Sgt. Dave
Thanks Joey, you're a great teacher.
Thanks so much for the informative video. This is much more clear and concise than the slides and book I've received from my database class.
Excellent
Thank you Joey, very helpful!
thanks answered my question🙂
Good explanation. After seeing the video, I felt like using pivot tables in Excel could speed up the process.
nice tutorial
THANK YOU this helped so much!
Nicely done Joey! Thank you...
Awesome
Very well explained. This video tied up a loose ends for me. I already knew how to break apart one table into other tables, but this explanation really helped me to 100% confdent. Wouldn't it be a good idea to put 'Product Manufacturer Address' into it's own table in case the product is manufactured in multiple locations? If so, then what would be the key to the 'Product Manufacturer Address' table?
The best one that i have seen!!
It was very well explained with example, thank you
In this video 20:16 how did you sort product key. if we double click on that will it save all the rows
Just awesome man!!!
Your tutorials are of no doubt ....
Kindly make video(s) on "Entity Diagrams"
Excellent Video.
waw impressive
hows does the qualntity depend on the order date? Can we just notpull the quantities using customer id and product?
Great video, Thanks!
But how are Dozen, Pack, Inch and $ atomic when they are combined with numbers?
Thanks for the video!
Pls tutor java,c#,assembly. Only one ofcourse. I only saying this
b/c u helped me a lot thank you very much.
Great stuff.
How would you deal with price changes over time? Do you need a separate Price table with dates or something?
Would be great to get your input.
Thanks, appreciate your content.
You’re amazing!
Hi Joey,
Do you offer training beside the online videos? you are good at this.
@Joey Blue Thank you for your videos. They are very helpful. Now about this specific video. Is it necessary to have a separate Customer order lines table? If we had an orders table with the product id as a 2nd FK and the quantity, wouldn't we also be in 4NF?
It all depends on what else you are storing in the orders table. Many times there are things that you want to store at the Order level. Maybe a flat Handling Fee that doesn't depend on the Product. You would need to figure out where to store that information without repeating it on every product line. There are many ways to do it, you just want to keep in mind the grain of the table and if you are unnecessarily repeating data.
Joey, please help with the download link for SQL server. I am starting SQL learning from your video.
Do we need to split the Customer address in example 1 to make it in 1st normal form as address seems to be composite attribute?
Thanks for the video, Joey! Pretty good explanation. I got with one doubt in the end. What is the PK for the Customer mail catalog and the customer email subscription tables?
Thank you, that was helpful
How does product manufacturer depend on product if there is a manufacturer that has 2 diff products
This video is quite good. It would be great if you could keep doing more of these Database theory videos.
I noticed that Product ID - Basketball - SP is duplicate in product tabke so it is not qualified as Primary Key...?
sir my db is in mysql using MYISAM.... No foreign keys implemented with some columns repeating in tables as well... i have approximatelly 40 tables and all containns approx 500 rows.... but 5 or 6 tables contains above one million rows each....db is not normalized.....but it is still working fine...on LAN and on cloud as well ... what will be fuiture of my db...
Could the customer order table be further normalised to the 4nf by pulling out the customer order and order date?
Great stuff! Very helpful. Not to be picky but in trying to understand the "solution" I noticed (in the original large table) that Bob Smith made two purchases on 8/9 and the Order Total didn't add up to the total of the two lines. The total in the chart is $70...shouldn't it be $60 or am I missing something? Also should the "Customer Email Subscriptions" and "Customer Mail Catalogs" tables be JOIN tables? It seems that there is a Many-to-Many relationship between these tables and Customers (e.g.,, Customers can subscribe to Many Email subscriptions and an Email subscription can belong to many Customers). Seems like the classic situation for a Join table. Also currently the way you have it defined there is no primary key for these Email and Mail tables (as there are duplicates). Not sure if that is an issue. Thoughts?
Glad I found this.
1. Thanks for your video!
2. One of the "Basketball-SP" records under the "Products" table needs to be deleted.
3. Price for "Basketball-SP" needs to be updated in the original table ( @16:49). It should be either $23 or $25.
4. Order Totals for "Customer Order ID" #1 and #4 don't look correct ("Customer Orders" table).
Our teacher showed us this video.
That's how you explain normalisation.
I am the luckiest to be here.Thanks Sir
Isn't the Order Total field a Calculated field? Can it have a place in a table? If yes, how was it calculated here to show the results it exhibits here? Newbie here, thank you :)
Hi Joey, Thanks for the very instructional video. I do have a question. What do we do with the two ProductID Basketball-SP with different prices?
I think that was an oversight. They should either be the same price and then one of the rows would be deleted or the basketballs should be named to differentiate them (in the product column) like Basketball-yellow and Basketball-Orange.
You just add a different Product ID for the differently priced one.
one of 2 records needs to be deleted
which application are you using for this lesson?
In the section explaining 2NF, when deduping the Product Table, you got rid of two rows. The first I understand (Bat, Louisville Slugger) because it was a duplicate. However, you also got rid of (Basketball, Titleist) even though it wasn't a duplicate. Why? Great video!
so how you create in in sql .?
Big thanks from Dublin, Ireland! :)
In 8:30 your product table contains
basketball-Spaulding
basketball- titleist
and ypu just deleted basketball titleist and the supplier titleist supplying basketballs suddenly disappeared from the database.
im quite confused there
Having 2 basketball products in Product Table would no longer keep the Primary Key Unique
@@adityakolte2599 But he loses information by doing so - how can you know that Titleist produces basketballs? This is a bad choice of primary key. Clearly other manufacturers can produce basketballs, and manufacturers can produce more than one product. The solution would be a new product ID column, or a composite primary key of both columns. Thinking forward, a product ID would be better, as the same manufacturer could make the same product, with additionally added columns for e.g., descriptions (e.g., different colors, sizes)
@@nickbull7278 The author corrected the above table in 8:36, so that basketballs are produced only by Spaulding in the simple example. That way, the 2NF was correctly applied. But you right: if two different manufactures can produce the same product, there was no dependency in the above table; therefore, the products table should not have been created.
2nd Normal form
Why do we need order date to make a unique composite key, when customer and product are sufficient to make a primary key? Please answer the question, thanks
At 8:25, when normalizing to 2NF, Mark Smith has a Titleist basketball and Bob Smith has a Spaulding basketball. A few seconds later after deleting rows from the Product table, Mark Smith has a Spaulding (note: no longer Titleist) basketball. Manufacturer:Product was m:1 and then changed to 1:1 behind the scenes. This is confusing for those learning about normalization. It seems the error was noticed while recording and fixed "off camera" - it would be helpful to correct the error in the video for those of us following along. I was confused about how having just the product name as a foreign key could uniquely identify both the product and manufacturer when, at that point, two manufacturers had basketballs.
niemand gaat dit lezen broer
@@Kipviss behalve jou!
In the example for third normal form where you break out product manufacturer and adress to avoid redundancy and then declare manufacturer as foreign key in the original table, does that still not result in redundancy in the first table? The column of Product Manufacturer that you colored as foreign key still seems to have repeating values in the rows. I know the transitivity has been dealt with though.
Happy if somebody could explain this for me.
It is not possible (at least in this case) to completely eliminate redundancy. The goal is merely to reduce redundancy. The main goal in any case was to make it so a manufacturer's address is only specified in one place. Instead of repeating both the manufacturer and its address, it's much better to just repeat the manufacturer.
Assume you have a table User(id, email, username). All fields are unique. Does it satisfy 3NF?
Thank you very much.
Just wondering have I wrote the SQL correctly for this? Many thanks, Robert
CREATE DATABASE OrderLine
/* Create this table 1st */
Create Table ProductManufacturers(ProductManufacturer varchar(50) Primary Key ,
ProductManufacturerAddress varchar(50))
Insert into ProductManufacturers(ProductManufacturer,ProductManufacturerAddress) values('Spaulding', '1 Spalding way')
Insert into ProductManufacturers(ProductManufacturer,ProductManufacturerAddress) values('Louisville Slugger', '345 Slugger Avenue')
Insert into ProductManufacturers(ProductManufacturer,ProductManufacturerAddress) values('Rawlings', '23 Rawlings Court')
Insert into ProductManufacturers(ProductManufacturer,ProductManufacturerAddress) values('Titleist', '1234 Titlest Road')
/* Create this table 2nd */
Create Table CustomerEmailSubscription(CustomerID varchar(100) NOT NULL,
CustomerEmailSubscriptions varchar (100),
Primary Key(CustomerID,CustomerEmailSubscriptions))
Insert into CustomerEmailSubscription(CustomerID,CustomerEmailSubscriptions) values('bsmith1', 'Baseball')
Insert into CustomerEmailSubscription(CustomerID,CustomerEmailSubscriptions) values('bsmith1', 'Basketball')
Insert into CustomerEmailSubscription(CustomerID,CustomerEmailSubscriptions) values('jthomas1', 'Baseball')
Insert into CustomerEmailSubscription(CustomerID,CustomerEmailSubscriptions) values('bsmith2', 'Golf')
/* create this table 3rd */
Create Table CustomerMailCatalogs(CustomerID varchar(100),
CustomerMailCatalogs varchar(100),
Primary Key(CustomerID,CustomerMailCatalogs))
Insert into CustomerMailCatalogs(CustomerID,CustomerMailCatalogs) values('bsmith1', 'Baseball')
Insert into CustomerMailCatalogs(CustomerID,CustomerMailCatalogs) values('bsmith1', 'Basketball')
Insert into CustomerMailCatalogs(CustomerID,CustomerMailCatalogs) values('jthomas1', 'Baseball')
Insert into CustomerMailCatalogs(CustomerID,CustomerMailCatalogs) values('bsmith2', 'Baseball')
/*Create this table 4th*/
Create Table Customers(CustomerID varchar(100) Primary Key,
FirstName Varchar(100),
Surname Varchar(100),
CustomerAddress varchar(100),
CustomerEmail varchar(100))
Insert into Customers(CustomerID, FirstName,Surname,CustomerAddress,CustomerEmail) values ('bsmith1','Bob', 'Smith', '123 Broadway', 'bsmith@gmail.com')
Insert into Customers(CustomerID, FirstName,Surname,CustomerAddress,CustomerEmail) values ('jthomas1','Jill', 'Thomas', '12 Cockland grove', 'jthomas@gmail.com')
Insert into Customers(CustomerID, FirstName,Surname,CustomerAddress,CustomerEmail)values ('bsmith2','Jill', 'Thomas', '5 Maple Street', 'smith5@hotmail.com')
/*Create this table 5th*/
Create Table CustomerOrders(CustomerOrderID int Primary Key identity(1,1),
CustomerID varchar(100) references Customers(CustomerID),
OrderDate Date,
OrderTotal Float)
Insert into CustomerOrders(CustomerID,OrderDate,OrderTotal) values('bsmith1','8/9/2020', 70)
Insert into CustomerOrders(CustomerID,OrderDate,OrderTotal) values('jthomas1','8/10/2020', 57)
Insert into CustomerOrders(CustomerID,OrderDate,OrderTotal) values('bsmith1','8/10/2020', 23)
Insert into CustomerOrders(CustomerID,OrderDate,OrderTotal) values('bsmith2','8/10/2020', 88)
/*Create this table 6th*/
Create Table Products(ProductID VarChar(50) Primary Key,
Product Varchar(50),
ProductManufacturer Varchar(50) references ProductManufacturers(ProductManufacturer),
ProductDetails Float,
ProductCost Float)
Insert into Products(ProductID,Product,ProductManufacturer,ProductDetails,ProductCost) values('BasketBall-SP', 'Basketball','Spaulding',29.5, 25)
Insert into Products(ProductID,Product,ProductManufacturer,ProductDetails,ProductCost) values('Bat-L', 'Bat','Louisville Slugger',33, 35)
Insert into Products(ProductID,Product,ProductManufacturer,ProductDetails,ProductCost) values('Softball-R', 'Softball','Rawlings',4, 6)
Insert into Products(ProductID,Product,ProductManufacturer,ProductDetails,ProductCost) values('Bat-R', 'Bat','Rawlings',32, 45)
Insert into Products(ProductID,Product,ProductManufacturer,ProductDetails,ProductCost) values('Golfballs-T', 'Golf Balls','Titleist',12, 44)
Insert into Products(ProductID,Product,ProductManufacturer,ProductDetails,ProductCost) values('Basketball-T', 'Basketball','Titleist',12, 44)
/* Create this table 7th */
drop Table CustomerOrderLines
create Table CustomerOrderLines(ProductID varchar(50),
CustomerOrderID int,
quantity int,
Primary Key(ProductID,CustomerOrderID),
Foreign Key(ProductID) references Products(ProductID),
Foreign Key(CustomerOrderID) references CustomerOrders(CustomerOrderID))
Insert into CustomerOrderLines(ProductID,CustomerOrderID,Quantity) values('Basketball-SP',1,1)
Insert into CustomerOrderLines(ProductID,CustomerOrderID,Quantity) values('Bat-L',1,1)
Insert into CustomerOrderLines(ProductID,CustomerOrderID,Quantity) values('Softball-R',2,2)
Insert into CustomerOrderLines(ProductID,CustomerOrderID,Quantity) values('Bat-R',2,1)
Insert into CustomerOrderLines(ProductID,CustomerOrderID,Quantity) values('GolfBalls-T', 4, 2)
Insert into CustomerOrderLines(ProductID,CustomerOrderID,Quantity) values('Basketball-T', 4, 2)
select* FROM CustomerEmailSubscription
select * from ProductManufacturers
select * from Products
select * from Customers
@26:24
You have the OrderTotal for OrderID 1 as $70 (in the Customer Orders table) but didn't bsmith1 order two $70 products. Shouldn't the OrderTotal for OrderID 1(in the Customer Orders table) be $140?
same questions
those who haven't watched this video and searching for "DB Normalization" are even dumber than I am. This is a Life saver.
Maybe youtube is
Normalization might as well have been mandarin before now, thank you!