What is NULL ?
Null denotes that a data value which is not exist in the database. The term “NULL” has been coined by E.F.Codd.
Null usually represent Inapplicable or Missing information in the system. In SQL Server NULL is a keyword/reserved word.
Is Null as same as Zero ?
No, Missing or inapplicable information can’t be assumed as Zero value.
The price of a product can be a numeric value or “Don’t know the price”. If we don’t know the value of price then it will be classified as null.
SQL server uses the keyword NULL to differentiate among other data values.
A simple example to understand about null
SQL Code Snippet:
Declare @tabEmployee table (ID int, Namenvarchar(255), Department nvarchar(50), Salarydecimal(18,2))
Insert into @tabEmployee (ID,Name,Department,Salary)
Select ID ,Name,Department,Salary from@tabEmployee
Null for numeric data type:
It has been observed that we don’t have the department information about the employee Mark. Hence a null has been presented to denote the missing information.
Null for string data type:
As we don’t know the Department name for the employee Tom, it has been represented as NULL.
How to compare null value ?
As null is a special data value , it is not possible to compare using the equal sign.
Hence we need a special operator to handle values with NULL. The “IS NULL” operator will be useful to compare against the NULL data values.
The operator “IS NULL” can be used for string data types as well
Is zero length string or blank value is as same as Null ?
No, The below mentioned query and result set confirms the fact that only nullable values can be compared using “IS NULL”.
How to do Agile Estimates for SSRS report development? Agile estimation is an art and it will take reasonable time to gain experience. These simple steps will help you out. Step 1: Assess the complexity of the report by asking these high level questions How many sources have been involved? How many datasets need to […]
How do we improve our SQL knowledge and access what we know ?
The following links will help to improve SQL Server knowledge
You will learn about a specific topic in SQL Server. The stairway series are an excellent way to accelerate knowledge in no time.
You can find a solution to an uncommon problem here. Quick and easy to read tip in a page.
An SQL server encyclopaedia !. I can’t even imagine how he is able to write about each and every feature about SQL server.
A SQL book has been written in easy to understandable format. I love Rick Morelan’s examples for every concepts.
The SQL puzzles are a great way to access your knowledge. Its fun J. Take a challenge a day to improve your confidence.
I have written a post about online SQL Test
I have composed a set of basic SQL server questions below. This would help you to validate your understandings in the area of RDBMS, SQL Server, Data Types, SQL Functions, etc.
Please leave a comment, if you would like to add more questions.
What is continuous Integration and how this can be leveraged to enhance productivity for SSRS Report development?
Continuous Integration is a software practice of merging developer code into shared mainline repository different times a day.
Continuous Integration is an iterative process, in which we build, run test cases and deploy the components to validate the changes made by the developer. The developer will be notified with the results as soon as the changes have been made. This helps the developer to test the components as he/she develops.
Source Code Checkout for Build :
The CI framework (Build Plan) will checkout the source code from the source control. This code base will be built and the developer will be notified the outcome immediately. This helps the developer to fix the bug as soon as the changes have been checked-in. The build can be manual, scheduled or event driven (Based on the changes to code).
Validate the build:
The build can be validated by running a set of test cases. The success or failure of the test cases will help to validate the changes.
Test as we develop:
All of the above mentioned steps will happen in a short period of time (depends on the volume of the build assets). This helps to fix the bugs during the development.
Users of Continuous Integration (CI):
The CI framework mainly improves the development process. Hence the Developers and Test Engineers will greatly benefit from the process. This also helps to reduce the Release overhead for Release Engineer/Manager.
As the bug gets fixed early in the process, the business confidence will increase. Hence the project management is benefitted with the reduction in development time.
As CI is a practice , we need a tool to implement this. Jenkins CI is an open source CI tool. Below is a list of commercial CI tools in the industry
- Bamboo (Atlassian)
- TeamCity (JetBrains)
From the above details, it is prudent that Continuous Integration helps to self-test the code.
As the bugs get identified and fixed early in the development process, this helps to reduce the risk.
This process enables the cohesive and agile development methodologies.
- Read about Continuous Integration here (http://www.thoughtworks.com/continuous-integration)
- Comparison of CI Tools here (http://en.wikipedia.org/wiki/Comparison_of_continuous_integration_software)
- Stay Tuned for the next part to apply Continuous Integration for Reporting Services
- Watch my SQLBits 2015 presentation about CI for SSRS here and Download slides here
Today I have decided to write about “How to become a successful Independent IT consultant in the UK.
It requires lots of courage . The Independent consultant has to face so many challenges.
Key challenges need to be worked out are
- Maintaining financial stability
- Keep yourself updated about technology
- Polishing your soft skills day by day
- Maintaining emotional quotient during the market turmoil
However there are some ways to overcome these challenges
There are some recommendations to keep liquid cash to manage financial commitments for at least 3 months. This will give piece of mind that worst case scenario can be faced.
The least expensive way to learn soft skills and technology is to have online training subscription.
Maintaining Emotional Quotient:
This is one of the key skill an independent consultant need to concentrate on. As the job market fluctuates, it is mandatory to face the situation with the right mind set.
The following would help to maintain the balance
- Breathing exercises
- Simple aerobic exercises