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When is relation in 2NF?
A relation may be in 2NF if 1. it is in 1NF & 2. Every non prime attribute functional dependent on primary attribute
What do most database designer prefer 1NF 2NF or 3NF?
First normal form (1NF) sets the very basic rules for an organized database: * Eliminate duplicative columns from the same table. * Create separate tables for each group of related data and identify each row with a unique column or set of columns (the primary key). Second normal form (2NF) further addresses the concept of removing duplicative data: * Meet all the requirements of the first normal form. * Remove subsets of data that apply to multiple rows of a table and place them in separate tables. * Create relationships between these new tables and their predecessors through the use of foreign keys. Third normal form (3NF) goes one large step further: * Meet all the requirements of the second normal form. * Remove columns that are not dependent upon the primary key. Finally, fourth normal form (4NF) has one additional requirement: * Meet all the requirements of the third normal form. * A relation is in 4NF if it has no multi-valued dependencies. Remember, these normalization guidelines are cumulative. For a database to be in 2NF, it must first fulfill all the criteria of a 1NF database.
Define a truth table?
A truth table is usually a table in which the truth or falsehood of two variables are taken as input and these form the edges of the table. The content of the table shows the truth value of the result of some operation on the variables.
Show an example of a frequency table?
A frequency table is a table that shows in numbers how many items are in several categories.
Parts of the Frequency Table - 37k?
parts of frequency table
When is relation in 2NF?
A relation may be in 2NF if 1. it is in 1NF & 2. Every non prime attribute functional dependent on primary attribute
What is second normal form in DBMS?
Second normal form is valid in a table which have composite primary key which is made with the combination of two columns.So if we have A,B,C,D,E attributes in our table and C,D are fully functional dependent on A,B.But E is partially functional dependent on A,B,Mean if we use Only B to define E coloumn then that will be suffecent.so then we use 2nd normal form & we create two tables with coloumns attributes A,B,C,D and the other table with coloumns attribute B,E.That will be called second normal form.
Explain suitable example 1NF 2NF 3NF?
Sure! 1NF (First Normal Form): Each column in a table should hold atomic values (values that cannot be divided further), and each row should be unique. 2NF (Second Normal Form): Every non-key attribute must be fully functionally dependent on the entire primary key, meaning no partial dependencies are allowed. 3NF (Third Normal Form): In addition to 2NF rules, no transitive dependencies should exist, meaning that non-key attributes should not depend on other non-key attributes.
What are the three primary components of a form in Modern database management?
the three forms of database are in normalization called 1NF, 2NF, and 3NF
What kind of normal form data does the object-oriented database handle?
BCNF, 3NF, 2NF, 1NF Non First Normal Form Both
What is second normal form and explain it with simple example?
Example: The following relation is in First Normal Form, but not Second Normal Form:Order #CustomerContact PersonTotal1Acme WidgetsJohn Doe$134.232ABC CorporationFred Flintstone$521.243Acme WidgetsJohn Doe$1042.424Acme WidgetsJohn Doe$928.53In the table above, the order number serves as the primary key. Notice that the customer and total amount are dependent upon the order number -- this data is specific to each order. However, the contact person is dependent upon the customer. An alternative way to accomplish this would be to create two tables:CustomerContact PersonAcme WidgetsJohn DoeABC CorporationFred FlintstoneOrder #CustomerTotal1Acme Widgets$134.232ABC Corporation$521.243Acme Widgets$1042.424Acme Widgets$928.53The creation of two separate tables eliminates the dependency problem experienced in the previous case. In the first table, contact person is dependent upon the primary key -- customer name. The second table only includes the information unique to each order. Someone interested in the contact person for each order could obtain this information by performing a JOIN operation.
What is the population of Llangadog Wales?
1303 in 2001The resident population of Llangadog, as measured in the 2001 Census, was 1951 of which 49% were male and 51% were female.http://piurl.com/2Nf
Where is the Lawley Extension situated?
I believe the Lawley Extension is situated in England,see address below for the Telford Steam Railway:The Old Loco ShedBridge RoadHorsehayTelfordShropshireTF4 2NF
What do most database designer prefer 1NF 2NF or 3NF?
First normal form (1NF) sets the very basic rules for an organized database: * Eliminate duplicative columns from the same table. * Create separate tables for each group of related data and identify each row with a unique column or set of columns (the primary key). Second normal form (2NF) further addresses the concept of removing duplicative data: * Meet all the requirements of the first normal form. * Remove subsets of data that apply to multiple rows of a table and place them in separate tables. * Create relationships between these new tables and their predecessors through the use of foreign keys. Third normal form (3NF) goes one large step further: * Meet all the requirements of the second normal form. * Remove columns that are not dependent upon the primary key. Finally, fourth normal form (4NF) has one additional requirement: * Meet all the requirements of the third normal form. * A relation is in 4NF if it has no multi-valued dependencies. Remember, these normalization guidelines are cumulative. For a database to be in 2NF, it must first fulfill all the criteria of a 1NF database.
Different normalisation forms in database?
There are several normal forms are available in DBMS.those are1NF,2NF,3NF,BCNF,4NF,PJNF(project Join),DKNF(Domain Key).
Is there a company in London called Richard and crockhart?
Not in London, but there is a legal practice called Richard And Crockhart in South England. Albion House, Albion Street, East Sussex, BN7 2NF
What are the disadvantages of 1NF and 2NF?
First Normal Form Disadvantages:It cannot support multi valued attributes.It does not suffer from redundancy and having no limit to placed on a number of values
