Normal forms

Rushdi Shams, Dept of CSE, KUET 1

Database Database SystemsSystems

Normal FormsNormal Forms

Version 1.0Version 1.0

2Rushdi Shams, Dept of CSE, KUET

NormalizationNormalization

It It avoids duplication of dataavoids duplication of data. Hence it is a . Hence it is a tool to avoid redundancy of datatool to avoid redundancy of data..

Theorists gave loads of “do this”, “do that” Theorists gave loads of “do this”, “do that” thing when relational model was first thing when relational model was first invoked. One of those were normal forms. invoked. One of those were normal forms. Applying those theories on databases are Applying those theories on databases are called normalizatoin.called normalizatoin.

But the fact is, But the fact is, in commercial in commercial environment, loads of works are done by environment, loads of works are done by not maintaining the normalization not maintaining the normalization theories 100%!theories 100%!


Why Normalization?Why Normalization?


Why Normalization? Why Normalization? (continued)(continued)

What if we want to delete the student no What if we want to delete the student no 34668? 34668?

Alas! We will lose information about Alas! We will lose information about DEDUCTIVE DATABASE, its lecturer name DEDUCTIVE DATABASE, its lecturer name and many more!and many more!

What if we want to update the lecturer to What if we want to update the lecturer to NICK WHITTAKER? We will have to put staff NICK WHITTAKER? We will have to put staff name as well as staff no for that!name as well as staff no for that!

What if we want to insert a new student with What if we want to insert a new student with number 38989? We cannot insert any student number 38989? We cannot insert any student who does not have any assessment criteria!who does not have any assessment criteria!


AnomaliesAnomalies An anomaly is a bad thing. Because it An anomaly is a bad thing. Because it

tends the data in a database tends the data in a database LOGICALLY get corrupted!LOGICALLY get corrupted!

There are mainly 3 types of anomaliesThere are mainly 3 types of anomalies1.1. Insert anomalyInsert anomaly2.2. Delete anomalyDelete anomaly3.3. Update anomalyUpdate anomaly

The reason why I switched to discuss The reason why I switched to discuss about anomaly- you will understand about anomaly- you will understand later!later!


Insert AnomalyInsert Anomaly

It is caused when an insertion takes It is caused when an insertion takes place in a child table, where there is place in a child table, where there is no record in the parent table!no record in the parent table!


Insert Anomaly Insert Anomaly (continued)(continued)

What if you try to What if you try to insert a book of J K insert a book of J K Rawlings into the Rawlings into the table left without table left without putting her name putting her name into the table into the table below?below?


Delete AnomalyDelete Anomaly

Caused when a data in the parent Caused when a data in the parent table is deleted before deleting all table is deleted before deleting all the related data from its child (ren) the related data from its child (ren) table(s).table(s).

Well, if you prefer a cascaded Well, if you prefer a cascaded deletion, no one would mind!deletion, no one would mind!


Delete Anomaly Delete Anomaly (continued)(continued)

Before deleting the Before deleting the data from the table data from the table below, if you below, if you delete data from delete data from table in right, what table in right, what do you think it is do you think it is gonna happen?gonna happen?


Update AnomalyUpdate Anomaly

It is kind of like delete anomaly. It is kind of like delete anomaly. Both the parent table and child(ren) Both the parent table and child(ren) table(s) should get updated table(s) should get updated concurrently!concurrently!


More JargonsMore Jargons

Well, before starting with Well, before starting with normalizations, you must need to normalizations, you must need to know some jargons. You already are know some jargons. You already are aware of anomalies. Let’s get into aware of anomalies. Let’s get into some more!some more!


Functional DependencyFunctional Dependency

Y is functionally dependent on X if Y is functionally dependent on X if the values of Y are determined by the values of Y are determined by the values of X.the values of X.

Y=X+1. In this case, Y is functionally Y=X+1. In this case, Y is functionally dependent on Xdependent on X

y=f(x). In this generic case, y is y=f(x). In this generic case, y is functionally dependent on x as well.functionally dependent on x as well.


Functional Dependency Functional Dependency (continued)(continued)

In this case, CURRENCY is In this case, CURRENCY is functionally dependent on FXCODEfunctionally dependent on FXCODE


DeterminantDeterminant

If X determines the values of Y, then If X determines the values of Y, then X will be called the determinant of YX will be called the determinant of Y

Y=X+1. In this case, X is Y=X+1. In this case, X is determinant of Y.determinant of Y.

y=f(x). In this case, x is determinant y=f(x). In this case, x is determinant of y as well.of y as well.


Determinant (continued)Determinant (continued)

In this case, FXCODE is determinant In this case, FXCODE is determinant of CURRENCY.of CURRENCY.


Transitive DependencyTransitive Dependency

If the value of Z is determined by Y If the value of Z is determined by Y and the value of Y is determined by and the value of Y is determined by X, then there is a transitive X, then there is a transitive dependency between X and Z.dependency between X and Z.

This dependency thus states the This dependency thus states the indirect dependency.indirect dependency.

BackBack


Transitive Dependency Transitive Dependency (continued)(continued)

In this case, RATE is dependent on In this case, RATE is dependent on CURRENCY. CURRENCY is CURRENCY. CURRENCY is dependent on COUNTRY. So, RATE dependent on COUNTRY. So, RATE is transitively dependent on is transitively dependent on COUNTRY.COUNTRY.


Candidate keyCandidate key It is the It is the minimal setminimal set of super key. of super key.

Say, from this example, you only can have Say, from this example, you only can have super keys as followings (though you may super keys as followings (though you may have other combinations, but just shorten have other combinations, but just shorten that this time)-that this time)-{roll, name}, {roll, name, dept}, {roll, {roll, name}, {roll, name, dept}, {roll, name, year, semester}name, year, semester}

In this case, the candidate key is {roll, name}!In this case, the candidate key is {roll, name}!

RollRoll NamNamee

DeptDept YearYear SemeSemesterster


Full Functional Full Functional DependencyDependency

If X determines Y but X with If X determines Y but X with combination of Z does not determine combination of Z does not determine Y- then, there is a full functional Y- then, there is a full functional dependency between X and Y.dependency between X and Y.

So, X cannot be a composite key.So, X cannot be a composite key.

Nb. If you make a key with 2 or Nb. If you make a key with 2 or more columns, then that is called a more columns, then that is called a composite key.composite key.


Full Functional Dependency Full Functional Dependency (continued)(continued)

In this case, In this case, POPULATION POPULATION depends on depends on COUNTRY not on the COUNTRY not on the combination of combination of RATE and RATE and COUNTRY. So, COUNTRY. So, POPULATION is fully POPULATION is fully functional dependent functional dependent on COUNTRY and on COUNTRY and also you can say that, also you can say that, POPULATION is not POPULATION is not fully functional fully functional dependent on RATE dependent on RATE and COUNTRY!and COUNTRY!


11stst Normal Form: 1NF Normal Form: 1NF Academic Definitions:Academic Definitions:1. Eliminate repeating groups such that

all records in all tables can be identified uniquely by a primary key in each table. In other words, all fields other than the primary key must depend on the primary key.

2. A relation is in first normal form if and only if every non-key attribute is functionally dependent upon the primary key


1 NF (continued)1 NF (continued)

3. A relation is in first normal form if the domains on which its attributes are defined are scalar

BackBack



Easy Definition:Easy Definition:

1 NF is a process of removing repeating 1 NF is a process of removing repeating groups from a table by creating a new groups from a table by creating a new tabletable

They are linked by a one to many They are linked by a one to many relationshiprelationship

Create primary keys on both tablesCreate primary keys on both tables

The child table will have a composite The child table will have a composite primary key (one of its own, other is its primary key (one of its own, other is its foreign key from its parent table)foreign key from its parent table)


What does 1 NF do?What does 1 NF do? Academic Way:Academic Way: Eliminates repeating groupsEliminates repeating groups Defines primary keysDefines primary keys No duplicate entry allowedNo duplicate entry allowed All fields other than primary key depend on All fields other than primary key depend on

primary keyprimary key All columns must contain a single value All columns must contain a single value

(see (see Definition 3Definition 3)) All values in a column must have the same All values in a column must have the same

data typedata type Create a table to move repeating data from Create a table to move repeating data from

the current tablethe current table


Not Scalar- Not 1 NFNot Scalar- Not 1 NF


Repeating Groups- Not 1 Repeating Groups- Not 1 NFNF


0 NF to 1 NF0 NF to 1 NF

Remove repeating Remove repeating groups. Split table groups. Split table into tables with into tables with one to many one to many relationship.relationship.


0 NF to 1 NF (continued)0 NF to 1 NF (continued)

Creating primary Creating primary key on parent table key on parent table and composite and composite primary key on primary key on child table (where child table (where it has a foreign key it has a foreign key referenced to referenced to parent table)parent table)


Our 1 NFOur 1 NF


Can you do it?Can you do it?


Yes! You Can!!Yes! You Can!!


Second Normal Form- 2 Second Normal Form- 2 NFNF

Academic Definition:Academic Definition:1. A relation is in second normal form if

and only if it is in first normal form and every non-key attribute is fully functionally dependent on the primary key

2.2. A relation is in second normal form if A relation is in second normal form if it is in first normal formit is in first normal form and, in and, in addition, addition, all its attributes are all its attributes are dependent on the entire candidate key dependent on the entire candidate key


What does 2 NF do?What does 2 NF do? Academic Way:Academic Way: The table is in 1 NFThe table is in 1 NF All non-key values must be functionally

dependent on the primary key. In other words, non-key fields not dependent on the primary key are not allowed.

Partial dependencies must be removed. A partial dependency is a special type of functional dependency that exists when a field is dependant on a part of a composite primary key.

Create a table with partially dependent part of the primary key and its dependents.


Which is not 2 NF?Which is not 2 NF?

Solution!Solution!


1 NF to 2 NF1 NF to 2 NF


Separating TablesSeparating Tables


Providing Many to One Providing Many to One RelationRelation


Providing One to Many Providing One to Many RelationshipRelationship


Can You Do It?Can You Do It?


Remember Me? I was not 2 Remember Me? I was not 2 NF!!NF!!

See Me!See Me!


33rdrd Normal Form- 3 NF Normal Form- 3 NF

Academic Way:Academic Way: The table must be in 2 NFThe table must be in 2 NF Eliminate transitive dependency (Eliminate transitive dependency (

see Transitive Dependencysee Transitive Dependency)) Create a new table to contain any Create a new table to contain any

separated columnsseparated columns


3 NF3 NF

Easy Way:Easy Way: Meet the requirements by 1 NF and Meet the requirements by 1 NF and

2 NF2 NF Remove columns that are not fully Remove columns that are not fully

dependent on the primary keydependent on the primary key


3 NF (case study)3 NF (case study)

Imagine we have a table that Imagine we have a table that contains the following columns-contains the following columns-

1.1. Order numberOrder number

2.2. Customer numberCustomer number

3.3. Unit priceUnit price

4.4. QuantityQuantity

5.5. Total Total


3 NF (case study): Checking 3 NF (case study): Checking if it is in 1 NFif it is in 1 NF





5.5. Total Total Are there duplicate columns? No!Are there duplicate columns? No! Do we have a primary key? Yes, the Do we have a primary key? Yes, the

order number!order number! Fine, it is in 1 NF then!!Fine, it is in 1 NF then!!



1.1. Order numberOrder number2.2. Customer numberCustomer number3.3. Unit priceUnit price4.4. QuantityQuantity5.5. Total Total Are there any static of data that Are there any static of data that

apply to multiple rows? No!apply to multiple rows? No! Fine, we are in 2 NF then!!Fine, we are in 2 NF then!!







5.5. Total Total Are all of the columns fully depend Are all of the columns fully depend

on the primary key (order on the primary key (order number)?number)?


3 NF (case study): Checking 3 NF (case study): Checking if it is in 3 NF (continued)if it is in 3 NF (continued)

The customer number varies with the order The customer number varies with the order number and it doesn't appear to depend number and it doesn't appear to depend upon any of the other fields upon any of the other fields

What about the unit price? This field could What about the unit price? This field could be dependent upon the customer number in be dependent upon the customer number in a situation where we charged each a situation where we charged each customer a set price. However, looking at customer a set price. However, looking at the data above, it appears we sometimes the data above, it appears we sometimes charge the same customer different prices. charge the same customer different prices. Therefore, the unit price is fully dependent Therefore, the unit price is fully dependent upon the order number upon the order number


3 NF (case study): Checking 3 NF (case study): Checking if it is in 3 NF (continued)if it is in 3 NF (continued)

The quantity of items also varies from The quantity of items also varies from order to order, so we're OK there. order to order, so we're OK there.

What about the total? It looks like we What about the total? It looks like we might be in trouble here. The total might be in trouble here. The total can be derived by multiplying the unit can be derived by multiplying the unit price by the quantity, therefore it's price by the quantity, therefore it's not fully dependent upon the primary not fully dependent upon the primary key. We must remove it from the table key. We must remove it from the table to comply with the third normal form. to comply with the third normal form.


3 NF (case study): Making 3 NF (case study): Making it a 3 NFit a 3 NF

1.1. Order numberOrder number2.2. Customer numberCustomer number3.3. Unit priceUnit price4.4. QuantityQuantity Now, the table is in 3 NF. What Now, the table is in 3 NF. What

about total? Well, there is no need to about total? Well, there is no need to put it on a separate table! You can put it on a separate table! You can make a select command to grab the make a select command to grab the total by multiplying unit price with total by multiplying unit price with quantity- can’t you?quantity- can’t you?


3 NF3 NF

Did you see the Did you see the irrelevant columns irrelevant columns in the 2 tables?in the 2 tables?

You need to You need to separate them!separate them!



Eliminated the Eliminated the irrelevant columns irrelevant columns and making them a and making them a separate table.separate table.



Can you see the Can you see the irrelevant column irrelevant column here?here?

You need to You need to separate them to separate them to make it a 3 NF!make it a 3 NF!



Did you see the Did you see the column that does column that does not depend on the not depend on the primary key?primary key?

You need to You need to separate that separate that column from the column from the table to make it 3 table to make it 3 NFNF


Can you do it?Can you do it?


Be warned!Be warned!

3 NF is said to be the most crucial 3 NF is said to be the most crucial and most ambiguous, most complex and most ambiguous, most complex part of normalization! part of normalization!


Bad thing of too much Bad thing of too much normalizationnormalization

Did you take a look at the number of Did you take a look at the number of table increased from 0 NF to 3 NF? If it is table increased from 0 NF to 3 NF? If it is a big enterprise database, then can you a big enterprise database, then can you imagine how far this can go?imagine how far this can go?

Too many tables lead us to too many joinsToo many tables lead us to too many joins Joins are one of the complex codings and Joins are one of the complex codings and

time consuming subtle entities in time consuming subtle entities in database systemsdatabase systems

So, try to normalize, but don’t normalize So, try to normalize, but don’t normalize in a way that you have 1000 tables!in a way that you have 1000 tables!


Beyond 3 NFBeyond 3 NF

Most software development firms Most software development firms dealing with database systems do dealing with database systems do not go beyond 3 NF and many of not go beyond 3 NF and many of them even try not to reach 3 NF!!them even try not to reach 3 NF!!


Boyce Codd Normal Form Boyce Codd Normal Form (BCNF)(BCNF)

It is a variation of 3 NFIt is a variation of 3 NF In a 3NF table, all attributes are dependent In a 3NF table, all attributes are dependent

on a key, a whole key and nothing but a key on a key, a whole key and nothing but a key A table is said to be in BCNF if and only if A table is said to be in BCNF if and only if

it is in 3NF and every non-trivial, left-it is in 3NF and every non-trivial, left-irreducible functional dependency has a irreducible functional dependency has a candidate key as its determinant candidate key as its determinant

In more informal terms, a table is in BCNF In more informal terms, a table is in BCNF if it is in 3NF and the only determinants if it is in 3NF and the only determinants are the candidate keys are the candidate keys


BCNF (continued)BCNF (continued)



Primary key is product category and Primary key is product category and product subcategoryproduct subcategory

The table is in 3NF, for each of its non-key The table is in 3NF, for each of its non-key attributes is non-transitively dependent on attributes is non-transitively dependent on the full key (Product Category, Product the full key (Product Category, Product Subcategory). Subcategory).



Yet the table has redundant data. Look at Yet the table has redundant data. Look at column 1, column 3 and column 4 for the column 1, column 3 and column 4 for the last 4 rows!last 4 rows!



Indeed, Range Code is dictated by the combination of Indeed, Range Code is dictated by the combination of Product Category and Stock Category Product Category and Stock Category

Is stock category a candidate key? NO! Then it is not in Is stock category a candidate key? NO! Then it is not in BCNF!!BCNF!!


BCNF (continued)BCNF (continued) The point about BCNF is that a candidate

key is, by definition, a unique key, and thus a potential primary key.

If a table contains more than one candidate key (primary key), it has a problem according to BCNF. I disagree!

BCNF divides a table up into multiple tables to ensure that no single table has more than one potential primary key

BCNF prohibits a table from having two possible primary keys.


Anomaly problemAnomaly problem

In this table, say, studentNo and Area is In this table, say, studentNo and Area is primary keyprimary key



What if 123456 wants to change her subject to What if 123456 wants to change her subject to information systems? We will lose the data-information systems? We will lose the data-

who is taking the course computer science?who is taking the course computer science? This is update anomalyThis is update anomaly



What if staff 250 also will take computer What if staff 250 also will take computer science? If there is no student enrolled in science? If there is no student enrolled in that subject, then we cannot insert that that subject, then we cannot insert that information in this table!!information in this table!!

This is insert anomalyThis is insert anomaly



What if 123456 wants to withdraw from the What if 123456 wants to withdraw from the course Software Engineering? We will lose course Software Engineering? We will lose the data-the data-Who will take the course Software Engineering!!Who will take the course Software Engineering!!

This is delete anomalyThis is delete anomaly


Why anomaly?Why anomaly?

The anomalies occurred because, The anomalies occurred because, there are two overlapping candidate there are two overlapping candidate keys- student number and area!keys- student number and area!


Normalizing to BCNFNormalizing to BCNF Suppose a relation R is not in Suppose a relation R is not in BCNFBCNF. Then there must . Then there must

be some functional dependency X → A where X is not be some functional dependency X → A where X is not a superkey.a superkey.

In this case, the relation can be decomposed into the In this case, the relation can be decomposed into the two relations two relations

1.1. R1= R − AR1= R − A2.2. R2= XAR2= XA where R − A simply means dropping the attribute A where R − A simply means dropping the attribute A

from the schema and XA is the relation whose from the schema and XA is the relation whose attributes are those in X together with Aattributes are those in X together with A

Then examine the new tables if you can apply 1 and 2 Then examine the new tables if you can apply 1 and 2 on them again!on them again!

When you cannot apply 1 and 2 on them, then it’s in When you cannot apply 1 and 2 on them, then it’s in BCNF!!BCNF!!


BCNF ExampleBCNF Example

Product category+stock category determines range Product category+stock category determines range code.code.

So, make two tables.So, make two tables.1.1. Product category, product subcategory, stock Product category, product subcategory, stock

category, range subcodecategory, range subcode2.2. Product category, stock category, range codeProduct category, stock category, range code


BCNF example BCNF example (continued)(continued)



Now, observe this new table. In it, the range Now, observe this new table. In it, the range subcode depends on stock category and product subcode depends on stock category and product subcategory. So, make two tables.subcategory. So, make two tables.

1.1. Product category, product subcategory, stock Product category, product subcategory, stock categorycategory

2.2. Product subcategory, stock category, range subcodeProduct subcategory, stock category, range subcode


Our tables in BCNFOur tables in BCNF


Fourth Normal Form (4 Fourth Normal Form (4 NF)NF)

A table must be in 3 NF or BCNF with 3 NFA table must be in 3 NF or BCNF with 3 NF Multi-valued dependencies must be transformed

into functional dependencies. This implies that one value and not multiple values are dependent on a primary key.

Eliminate multiple sets of multiple valued or multi-valued dependencies, sometimes described as non-trivial multi-valued dependencies.

NF and has no multiple sets of multi-valued dependencies. In other words, 4NF states that no entity can have more than a single one-to-many relationship within an entity if the one-to-many attributes are independent of each other.


4 NF Example4 NF Example

In this table, there In this table, there are 3 columns. are 3 columns. Employee, skill Employee, skill and skilllanguageand skilllanguage

Employee is the Employee is the primary keyprimary key

The table is in The table is in BCNF with 3NFBCNF with 3NF



The record for The record for employee number employee number 0122443 can be 0122443 can be written also in the written also in the form-form-

0122443: Typing, 0122443: Typing, Dictation: English, Dictation: English, French in the form French in the form employee: skill: employee: skill: skilllanguageskilllanguage



So, the multivalued So, the multivalued dependency is on dependency is on skill column and skill column and skilllanguage skilllanguage column!column!

To make it in 4 NF, To make it in 4 NF, you will have to you will have to simply split them simply split them into separate table, into separate table, nothing else!!nothing else!!


Solving one, creates Solving one, creates another problem!another problem!

Can you say, what is the problem Can you say, what is the problem still with the tables?still with the tables?

There are still 2 entries for the same There are still 2 entries for the same employee!!employee!!


Fifth Normal Form (5 Fifth Normal Form (5 NF)NF)

Personally, I really hate this form!!Personally, I really hate this form!! The table must have to be in 4 NF The table must have to be in 4 NF

(same old dialogue!)(same old dialogue!) The table should not contain any The table should not contain any

cyclic dependency!cyclic dependency! Cyclic dependency is like say your Cyclic dependency is like say your

table has 3 columns. Column 1 table has 3 columns. Column 1 depends on 2, 2 on 3 and 3 on 1!!depends on 2, 2 on 3 and 3 on 1!!

Also known as PJNF (Projection Also known as PJNF (Projection Normal Form)Normal Form)



Try begin with creating a table EmployeesTry begin with creating a table Employees All the 3 columns are primary key (kind of All the 3 columns are primary key (kind of

weird, isn’t it?? We can call it composite weird, isn’t it?? We can call it composite primary key)primary key)



Let’s insert some data in Employees table Let’s insert some data in Employees table then.then.



Employees table now look like this!Employees table now look like this! There is no multivalued dependency, so, There is no multivalued dependency, so,

the table is in 4 NF (of course also in 1-2-the table is in 4 NF (of course also in 1-2-3-BC NF!!)3-BC NF!!)



Now, let’s play with the basic table Employees. Now, let’s play with the basic table Employees. We will split the table into three tables. WHY? We will split the table into three tables. WHY? I will say you later.I will say you later.

We are making three tables- project_employee, We are making three tables- project_employee, project_manager, manager_employeeproject_manager, manager_employee


Detail of Detail of project_employeeproject_employee


Detail of Detail of project_managerproject_manager


Detail of Detail of manager_employeemanager_employee


The Fun!The Fun! Now, we will query the initial table Employees! It Now, we will query the initial table Employees! It

will show us the whole tablewill show us the whole table


The Fun Continues!The Fun Continues!

Now, we will join the three new tables Now, we will join the three new tables and will get the same answer!!and will get the same answer!!


So, what is the fun for?So, what is the fun for?

The fun is, if you have a table in 4 The fun is, if you have a table in 4 NF but with cyclic dependency, if NF but with cyclic dependency, if you can split it into x number of you can split it into x number of tables and then while joining those x tables and then while joining those x number of tables, it will give you number of tables, it will give you back the initial table, you then made back the initial table, you then made it 5 NF while splitting!it 5 NF while splitting!

Phew!!Phew!!


Domain Key Normal Form Domain Key Normal Form (DKNF)(DKNF)

Please god, help us! There are loads of Please god, help us! There are loads of normal forms! I cannot go beyond that! normal forms! I cannot go beyond that! Well, folks, this one is the last- I Well, folks, this one is the last- I promise!!promise!!

Domain/key normal form (DKNF) is a Domain/key normal form (DKNF) is a normal used in database normalization normal used in database normalization which requires that the database which requires that the database contains no constraints other than contains no constraints other than domain constraints and key constraints. domain constraints and key constraints.


DKNF (continued)DKNF (continued)

This table violates the rules for being DKNFThis table violates the rules for being DKNF If Wealthy person type is Eccentric Millionaire/ evil If Wealthy person type is Eccentric Millionaire/ evil

millionaire, then the Net Worth in Dollars must be millionaire, then the Net Worth in Dollars must be 1,000,000 to 999,999,999 inclusive and if that is 1,000,000 to 999,999,999 inclusive and if that is Evil Billionaire/ Eccentric Billionaire, then it should Evil Billionaire/ Eccentric Billionaire, then it should be 1,000,000,000 or higher. be 1,000,000,000 or higher.


So, what to do?So, what to do?

Nothing serious, the violation on domain can Nothing serious, the violation on domain can be solved easily by changing the domain of be solved easily by changing the domain of Wealthy Person Type to Eccentric and Evil- Wealthy Person Type to Eccentric and Evil- forget about Millionaire and Billionaire!!forget about Millionaire and Billionaire!!

It is then in DKNF!!It is then in DKNF!!


The Flow chartThe Flow chart

Say, you are given a table in 0 NF. Do Say, you are given a table in 0 NF. Do the followings one by one-the followings one by one-

1.1. Are there duplicate rows? Find the Are there duplicate rows? Find the answer Noanswer No

2.2. Is there primary key? Find the answer Is there primary key? Find the answer yes (then you finished making it in 1 NF)yes (then you finished making it in 1 NF)

3.3. Are all the non-key columns functionally Are all the non-key columns functionally depend on primary key? Find the depend on primary key? Find the answer yes (then you finished making it answer yes (then you finished making it 2 NF)2 NF)


The Flow Chart The Flow Chart (continued)(continued)

4.4. Are all the columns that are non key Are all the columns that are non key depending fully functionally upon the primary depending fully functionally upon the primary key? Find the answer yes (then you made it key? Find the answer yes (then you made it into 3 NF)into 3 NF)

5.5. Are all the determinants candidate key of the Are all the determinants candidate key of the table? Find the answer yes (then you made it table? Find the answer yes (then you made it into BCNF)into BCNF)

6.6. Are there multivalued dependency? Find the Are there multivalued dependency? Find the answer no (then you made it into 4 NF)answer no (then you made it into 4 NF)

7.7. Are there any cyclic dependency? Find the Are there any cyclic dependency? Find the answer no (then you made it into 5 NF)answer no (then you made it into 5 NF)

8.8. Are there any violation to domain Are there any violation to domain constraints? Find the answer no (then you constraints? Find the answer no (then you made it into DKNF)made it into DKNF)


ReferencesReferences Designing Effective Database Designing Effective Database

Systems by Rebecca M. Riordan, Systems by Rebecca M. Riordan, Addison Wesley Professional, 2005Addison Wesley Professional, 2005

Database Systems by Paul Beynon-Database Systems by Paul Beynon-Devies, Palgrave Macmillan, 2004Devies, Palgrave Macmillan, 2004

www.wikipedia.orgwww.wikipedia.org Beginning Database Design by Beginning Database Design by

Gavin Powell, Wrox Publications, Gavin Powell, Wrox Publications, 20052005


References (continued)References (continued) www.techtarget.comwww.techtarget.com http://http://databases.about.comdatabases.about.com Databases –Normalization by Gordon Databases –Normalization by Gordon

Royle, Department of Computer Royle, Department of Computer Science & Software Engineering Science & Software Engineering University of Western AustraliaUniversity of Western Australia

Database Management Systems by Database Management Systems by Prof. Holowczak, Zicklin School of Prof. Holowczak, Zicklin School of Business, Baruch College, City Business, Baruch College, City University of New YorkUniversity of New York

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