Ten Common Database Design Mistakes

I recently chanced upon an article written by Louis Davidson titled "Ten Common Database Design Mistakes". The article summarizes the list of critical mistakes that should be avoided while designing a database.

As the author humbly points out in the article, the list also summarizes the mistakes he too did during the early stages of his career. I liked the article as I had to endure the same learning curve as the author.

Here's a summary of the most common mistakes :-

1. Poor design/planning
2. Ignoring normalization
3. Poor naming standards
4. Lack of documentation
5. One table to hold all domain values
6. Using identity/guid columns as your only key
7. Not using SQL facilities to protect data integrity
8. Not using stored procedures to access data
9. Trying to build generic objects
10. Lack of testing

I couldn't have summarized it better !

MouseTrap

Another "gem" that I received in today's mail :-

A mouse looked through the crack in the wall to see the farmer and his wife open a package.

"What food might this contain?" The mouse wondered - he was devastated to discover it was a mousetrap.

Retreating to the farmyard, the mouse proclaimed the warning.

"There is a mousetrap in the house! There is a mousetrap in the house!"

The chicken clucked and scratched, raised her head and said, "Mr. Mouse, I can tell this is a grave concern to you but it is of no consequence to me. I cannot be bothered by it."

The mouse turned to the pig and told him, "There is a mousetrap in the house! There is a mousetrap in the house!"

The pig sympathized, but said, "I am so very sorry, Mr. Mouse, but there is nothing I can do about it but pray. Be assured you are in my prayers."

The mouse turned to the cow and said, "There is a mousetrap in the house! There is a mousetrap in the house!"

The cow said, "Wow, Mr. Mouse. I'm sorry for you, but it's no skin off my nose."

So, the mouse returned to the house, head down and dejected, to face the farmer's mousetrap-- alone.

That very night a sound was heard throughout the house -- like the sound of a mousetrap catching its prey.

The farmer's wife rushed to see what was caught. In the darkness, she did not see it was a venomous snake whose tail the trap had caught.

The snake bit the farmer's wife. The farmer rushed her to the hospital and she returned home with a fever. Everyone knows you treat a fever with fresh chicken soup, so the farmer took his hatchet to the farmyard for the soup's main ingredient.

But his wife's sickness continued, so friends and neighbors came to sit with her around the clock. To feed them, the farmer butchered the pig.

The farmer's wife did not get well; she died. So many people came for her funeral, the farmer had the cow slaughtered to provide enough meat for all of them.

The mouse looked upon it all from his crack in the wall with great sadness.

So, the next time you hear someone is facing a problem and think it doesn't concern you, remember -- when one of us is threatened, we are all at risk.

We are all involved in this journey called life. We must keep an eye out for one another and make an extra effort to encourage one another.


REMEMBER:
EACH OF US IS A VITAL THREAD IN ANOTHER PERSON'S TAPESTRY; OUR LIVES ARE WOVEN TOGETHER FOR A REASON.

Health Care : HL7 V3 Foundation Documents

The HL7 V3 Foundation documents provide rich insight into this wonderful standard. The Foundation Documents are very well organized & are comfortable to read.

You can find the foundation documents here.

The Foundation Document details the new approach in HL7 V3 :-

• HL7 V3 adopts an Object Oriented (OO) approach using Unified Modeling Language (UML) principles.

• Reduced Optionality. Limiting optionality is a primary goal of HL7 V3. Within HL7 V2.x, almost every field is optional.Optionality makes it harder to precisely define the semantics of a specific message and makes it virtually impossible to generate conformance claims for messaging.

• Conformance to HL7 V3 will be testable.

The Foundation documents are the best starting point to learn the HL7 V3 Standard.

Health Care : HL7 Standard

" Health Level Seven (HL7), is an all-volunteer, not-for-profit organization involved in development of international healthcare standards. “HL7” is also used to refer to some of the specific standards created by the organization (i.e. HL7 v2.x, v3.0, HL7 RIM etc.).

HL7 and its members provide a framework (and related standards) for the exchange, integration, sharing and retrieval of electronic health information. "

- Wikipedia

HL7 is a standard for Medical Applications to exchange information.

The Health Care industry segment is divided into many domains such as patient care, laboratory information systems, etc. The HL7 standard enforces a consistency of stored and shared information across many domains in Health Care.

The HL7 standard is continously being developed and enriched with new ideas. The HL7 committee has released six versions of the HL7 standard ( collectively called as HL7 2.x ) :

• 2.1
• 2.2
• 2.3
• 2.3.1
• 2.4
• 2.5

Hl7 2.x is the first widely accepted and commercially successful standard. HL7 v2.x mostly uses a proprietary (non-XML) encoding syntax based on delimiters.

HL7 3.0 is a complete rework of the HL7 standard. HL7 3.0 is an attempt to overcome some of the issues with HL7 2.x. XML is medium for exchange of HL7 messages instead of the simple ASCII text that HL7 2.x used.

The basis of HL7 v3.0 is a model called the Reference Information Model ( RIM ). RIM is an attempt to further standardize the HL7 specifications between health care systems.

The differences between HL7 2.x and HL7 3.x are :-

HL7 2.x

• HL7 2.x is the most popular and the most widely implemented HL7 standard in the US.
  
• HL7 2.x does not have a common information model that spans all Health care domains-of-interest.
• HL7 2.x does not have a robust data type specification.

HL7 3.x

• HL7 3.x is based on the RIM and attempts to bring consistency across the entire standard.
• HL7 3.x defines a common information model based on the RIM.
• HL7 3.x defines a data type specification.
  
• HL7 3.x is NOT backward compatible with HL7 2.x.
  

HL7 V2 is focussed on the exchange of clinical clinical data between applications. However, HL7 V3 is influenced by dedicated people who focus on how health care information is created & how it can be modeled.

HL7 v3.0 is a dramatic shift from HL7 2.x and introduces a lot of new concepts.

Health Care : Stakeholders interested in EHR

A Patient's EHR is of great interest to many stakeholders in the Health Care Industry. Each Stakeholder is interested in different aspects of a EHR.

The important Stakeholders in the Health Care Industry are :-

• Patient
  
• Providers
• Payors
• Suppliers
• Academic Centers
• Government

The interests of these Stakeholders vary - however, the source of information that will validate their assumptions and provide factual data is the EHR.

The primary interests of these Stakeholders can be summarized thus :-

• Patient : too understand the nature of the current ailment
  
• Providers : the understand the Medical History of the patient.
  
• Payors : Insurance Companies, etc.
  
• Suppliers : to understand the current supply / demand for Drugs, etc.
  
• Academic Centers : to understand the current trends in the field & research.
  
• Government : to understand the overall health status of the citizens in the country.
  

E.g; If a patient is admitted to a new Hospital, the doctors would definitely be interested to know the Medical History of the patient & the treatment administered by other Providers.

Hence, it is important that the EHR follow a standard. The standard should allow the Stakeholders to query the stored information or a subset of the information.

The standard for the EHR should address consistency in two areas :-

1. Storage of the data
2. Retrieval of the data ( entire data / a subset of the data ).

Health Level 7 ( HL7 ) is an international standard for storing and sharing clinical Health Information. HL7 is used to exchange EHR information as well as many other details across various Health care domains.

Health Care : Patient and Medical Record

The Health Care Industry is centered around the services that can be offered to a Patient. Patients and their Health Records offer tremendous insight into Medical Histories and is of great interest to many Stakeholders.

A Patient is a person in need of Medical attention. The Medical attention could be care and treatment.

The outcome of the Medical attention is :-

1. a Medical Record
2. a Bill for the offered Services.

The Medical Record is a documentation of :-

1. Observations made by the attending Medical Professional.
2. Recommended Scans to study the problem further.
3. Recommended care / Treatment.

A collection of Medical Records is the Medical History of the patient. However, the term "Medical Record" is also used interchangeably to include the Medical History ( Health Record ) of the patient.

An Electronic Medical Record ( EMR ) is a Medical Record in digital format. An EMR contains patient information from a single Health Care Provider ( a Doctor, a Hospital, etc. ).

An Electronic Health Record ( EHR ) contains patient information from multiple Health Care Provider ( Doctors, Hospitals, etc. ). Hence, an EHR can be considered as a collection of EMRs ( this is my view of EMR and EHR ).

Hence, a Health Care Provider contributes vital information about a Patient in the form of an EMR. The EMR in turn forms a vital component of a Patient's EHR.

Health Care : What is Healthcare

" Health care, or healthcare, is the prevention, treatment, and management of illness and the preservation of mental and physical well being through the services offered by the medical, nursing, and allied health professions. "

- Wikipedia

I wanted to write about IT in Health Care and my understanding & views. I use the Health Care category in my Blog to categorize my learning & organize it.

I have miles to go in learning an industry as exciting and diverse as Health Care - this section of my Blog is an attempt to capture my understanding and share it with the world.

Please do let me know your thoughts & perspectives on the topics I have shared here.

Network Troubleshooting - 2 : Check the Adapters

Check the Network Card.

A network card, network adapter, LAN Adapter or NIC (network interface card) is a piece of computer hardware designed to allow computers to communicate over a computer network.

- Wikipedia

A Network card allows you to send / receive messages to / from other computers in the same Network. Hence, the next obvious checkpoint is the Network Card.

You can use the simple PING command to ensure that the Network Card is working as expected. You just need to open a Command Prompt ( Terminal in LINUX ) & type :-

ping localhost

You should see a reply from the Network Card like this :-

Pinging sandeep-personal [127.0.0.1] with 32 bytes of data:

Reply from 127.0.0.1: bytes=32 time 1ms TTL=128
Reply from 127.0.0.1: bytes=32 time 1ms TTL=128
Reply from 127.0.0.1: bytes=32 time 1ms TTL=128
Reply from 127.0.0.1: bytes=32 time 1ms TTL=128

If you don't get this response, you can conclude on these :-

1. The Network Card is not properly installed.
2. The Network Card is not properly configured.
3. The Network Card is no longer functional.

Now, it's time to call up the IT Help Desk & tell them that there's a problem with the Network Card.

At the end of this exercise, you have :-

* tried some basic troubleshooting steps.
* identified the source of the problem.
* communicated effectively to the IT Support Staff.

You can now confidently communicate with the IT Support Staff & they'd be more than happy to work with an "educated" colleague.

Network Troubleshooting - 1 : Check the Cables

Check the Cables !

Yes, the most simplest method is toe check if Network Cable is properly connected to the computer.

Here's a small Checklist that I use :-

* The Network Cable is connected correctly to the Network Card (usually, rear of the Computer)
* The Network LEDs are flashing green - continuous or blinking.

If any of the above are not correct, I am sure there's something wrong with connection. If the Cable is connected correctly & your computer is still unable to get on the Network, you might want to try with a new Network Cable.

If it works - you have solved the problem :)

If you don't get this response, you can conclude on these :-

1. The Network Card is not able to get a signal from the Network.
2. The Network Card is not properly installed.
3. The Network Card is not properly configured.
4. The Network Card is no longer functional.

Now, it's time to call up the IT Help Desk & tell them that there's a problem with the Network Card.

At the end of this exercise, you have :-

* tried some basic troubleshooting steps.
* identified the source of the problem.
* communicated effectively to the IT Support Staff.

You can now confidently communicate with the IT Support Staff & they'd be more than happy to work with an "educated" colleague.

Network Troubleshooting - 0 : Need

A fairly good understanding of Networking concepts is important if your are working on a Multi-Tiered Distributed Project.

You could be working on JEE or any other Technology stack - without a basic understanding of he underlying network, you will frequently find yourself wondering why some of the components "don't talk to each other".

You need to have a basic understanding of the underlying Network, a few common problems & simple troubleshooting. It will help you articulate the nature of the problem to your Stakeholders & most importantly to your IT Help Desk Staff.

I also ask a few networking questions during my interview sessions to gauge if the candiate if aware of some of the basic facts.

I am definitely not an expert in Networking, but I would like to share some observations from my limited experience.

EJB 3.1 : Formation of the Expert Group

The EJB 3.1 expert group is working on for the next version of the Java EE EJB specification.

EJB 3.0 brought simplicity to Java EE 5 by moving away from a heavyweight programming model. EJB 3.1 aims to build on those successes by moving further down the path of simplicity as well as adding a handful of much-needed features.

Here are a few interesting features :-

1. EJB Interfaces are Optional.
2. The Singleton Beans are Here
3. Support for direct use of EJBs in the servlet container
4. EJB Timer Service enhancements
5. Support for stateful web services via Stateful Session Bean web service endpoints.

Reza Rehman is one of the members of the EJB 3.1 Expert group. He has promised to write more articles in future regarding EJB 3.1.

You can get more information here :-

http://www.theserverside.com/tt/articles/article.tss?l=NewFeaturesinEJB3-1

User Requirements for User Interface Design

User interface is the face of your application & unless it thrills all the stakeholders, your Project is never going to be successful.

I often notice the same mistakes committed in User Interface Design at the early stages of a Project. Here are some of those "evils" :-

1. Scope : The Scope of the Project is usually not defined clearly & as a result, a lot of unwanted action items creep into the scope.

2. Ambiguity : Often, the lack of clarity in defining a particular requirement leads to multiple interpretations.

3. Assumptions : Often, the Developers assume things on the behalf of the Users. Again, this may lead to multiple interpretations.

4. StakeHolders : it's very important to involve all the Stakeholders in the Project ( Users, Managers, Developers, etc. ) early. Else, UI redesign might become the main focus of the Project !

Here are some thing that I do to capture the User Requirements ( on a Page/Page basis ) :-

1. Description
2. Trigger
3. Success & Failure Criteria.
4. Items on the page
5. Clairifications.

Oracle : SQL : TRUNC Function with DATE

The TRUNC Function can be used with a DATE Datatype to get interesting results. The TRUNC can be used to get the First Day of the Month, First Day of the year, etc.

SQL> SELECT TRUNC(SYSDATE,'YYYY') FROM DUAL;

TRUNC(SYS
---------
01-JAN-06

SQL> SELECT TRUNC(SYSDATE,'MM') FROM DUAL;

TRUNC(SYS
---------
01-JUN-06

LINUX : Swap Space

I just learnt how to increase the swap space in LINUX - this link is good :

http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/custom-guide/s1-swap-adding.html

JavaScript " null " and "undefined"

JavaScript :

I need to check if every object is null or undefined - if neither, I must proceed with the validation. Else, Javascript throws ugly errors on the screen.

Check for null

if(object!=null) // the object isn't null.

Check for undefined

if(object) // the object is not 'undefined'

JavaScript DOM

I just discovered that JavaScript DOM does have some problems - I ran into problems doing the cross - browser testing. Apprarently, some part of the code didn't work in Netscape & Mozilla.

E.g; IE recognizes the parentElement keyword but Netscae wants parentNode.

I need to scrouge the net for a compatibility list.........