Skip to main content

Some Database questions

Normalization is a set of rules used for the design of database tables and table are meant to be connected through relation ship. This set of rules are know as normalization. Normalization will avoid the repetitive entries, reduces the storage space, will avoid the need to restructure the table to accommodate new data. By doing the normalization you can increase the speed and flexibility of queries, summaries etc.

Data must be broken into the smallest unit as possible and should not contain any repetitive group of fields.

ID      Name                 Pet1   Pet2     Hours  Days  TotalHours/Week
1       Adarsh Soman    Cat    Cat2      5         5        25

Here name can be broken as first name and last name and pet repeating. So based on the first normal form the table will become as

ID      First Name      LastName  Pet    Hours  Days  TotalHours/Week
1        Adarsh           Soman       Cat       5         5        25


Each non key field should be fact about the field in the primary key. Here pet can be moved into a different table



ID      First Name      LastName  PetID    Hours  Days  TotalHours/Week
1        Adarsh           Soman       1           5         5        25


PetID  PetName
1         Cat
2         Dog

A non-key field should not depend upon the other non key field. Here 
In the above table TotalHours/Week is calculated by multiplying hours into days.(total=hours*days). So based on the third normal form we can remove it.





ID      First Name      LastName  PetID    Hours  Days  
1        Adarsh           Soman       1           5         5        


Process of putting one fact in numerous place is know as denormalization and we can tell its a vice versa of normalisation. By doing it we can increase the performance (increasing redundancy as well)

Comments

Popular posts from this blog

How to write secure mvc application using encrypting URL

There are lots ways available to write the secure Mvc application. In my experience I came across lots of secure application in public facing. I want to tell about some of the mechanism I followed.
1- encrypting the URL Parameters and preserving id's encrypted on the client side
1- I always make sure if I pass Id or any sensitive data into the view always make sure it's encrypted. By doing so make sure if we forced to use HTML.hidden or HTML.hidden for have the encrypted values, in action link if I pass any parameters from the client side (eg:- edit or create or navigating between different actions we can make sure that all the values are encrypted)
During the design of the actions results if it's http get I usually encrypt the sensitive data
[httpget]
Public actionresult display()
{
TestModel testModel=new TestModel();
testModel.id= encrypt(id);
Return View(testModel);
}
[httppost]
Public ActionResult Display(string id)
{
Guid d_id= new Guid(decrypt(id));
// do operati…

How to add a stored procedure in Entity Framework

Step1- Open the .edmx file
Step2- Right click in .edmx file and select Update Model from Database


Step3- Select Add tab, select Stored Procedures and select the procedure you want to add and click finish as shown in below figure a

Step4- Build the Entity Project to make sure nothing is broke

Step5- Right click on .edmx file and  select Model Browser



Step6- Model Browser Popup will appear as  below figure. Click on the Strored Procedures in PricingToolModel.Stroe and click the newly added SP (it will appear here)
Step7- The Add Function Import screen will appear

Based on the return we can set up.

If you are returning a multiple column Click on the Get Column Information First, then click the new Complex Type. After that you can see the Return of Collection will select the Complex and a complex type is generated by EF

If its returning scalar you can select which return type like int, string etc...

If its return entitty (means table) please select the correct table from the list..

Click…

Can we store wifi and use it later?

I started using WIFI almost 8 years back (in 2006) when I moved to the UK. Before that, during the engineering degree I studied about WIFI energetically for achieving grades. Nowadays it’s a common friend and every day without her presence, it is awful to envisage. One day my data allowance on the mobile run out and I want to go to an event in central London and want to use the GPS. I had to take map printout and follow the route. I depend a lot on GPS navigation rather than a paper map. So I reached the location half an hour later in the event. Eventually I missed the event and while walking back to the tube station I was thinking about storing the WIFI somehow and using it later, like a battery. People might think why can’t I carry a portable modem and a laptop, but I am thinking about much sophisticated device than that like a battery for the phone. Did anyone think about a life without batteries now? It is there since most of us on this planet born. In 1749 Benjamin Franklin firs…