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Showing posts from January, 2014

Frequently Asked Basic PostgreSQL Interview Questions and Answers

Frequently Asked Basic PostgreSQL Interview Questions and Answers PostgreSQL is the widely used open source database. If you are preparing for PostgreSQL interview, following list of basic PostgreSQL interview questions and answers might help you in your interview preparation. Following PostgreSQL interview questions and answers cover PostgreSQL basic concepts like feature and advantages of PostgreSQL, key difference between MySQL and PostgreSQL, basic PostgreSQL database administration commands and tools, general PostgreSQL database concepts like Stored Procedures, Functions, Triggers, Cursor, Index, Joins, Subqueries etc.  1. What is PostgreSQL? What do you know about PostgreSQL? PostgreSQL, often simply "Postgres", is an open-source object-relational database management system (ORDBMS) with an emphasis on extensibility and standards-compliance. It is released under the PostgreSQL License, a free/open source software license, similar to the MIT License. PostgreSQL is develo

16 PostgreSQL Database Administration Commands

16 PostgreSQL Database Administration Commands Following are basic PostgreSQL database administration commands which each PostgreSQL database administrator should know. These PostgreSQL database administration commands include creating users in PostgreSQL, setting up user credentials in PostgreSQL, change / update PostgreSQL user password, check whether PostgreSQL is up and running, commands to create, delete, drop, start, stop, restart, backup, restore PostgreSQL database, getting the list of all databases in PostgreSQL, finding out what version of PostgreSQL is running, PostgreSQL help and history commands, commands to get the list of all the tables in a PostgreSQL database, commands to turn on timing and checking how much time a query takes to execute, commands to see the list of available functions in PostgreSQL etc. Lets have a look on following PostgreSQL Database Administration Commands. 1. How to change PostgreSQL root user password? $ /usr/local/pgsql/bin/psql postgres postgre

How to load Help File (.chm file) in your Delphi Project using HTMLHelpViewer?

How to load Help File (.chm file) in your Delphi Project using HTMLHelpViewer? Having the help option in your Delphi project is very common in which you want to load the chm file. If you want to create such a functionality in your project, here is the solution. It is very simple in Delphi. Following are the steps which you require to implement help functionality in your Delphi Project. 1. Create a valid chm file and place it in a directory where your exe is placed. 2. Include a unit " HTMLHelpViewer " under your uses section. HTMLHelpViewer is needed to register a viewer for HTML help. 3. On the click of help menu button, put the following code: procedure TMyForm.ExecuteHelp(Sender: TObject); begin   If Application.HelpFile <> '' then     Application.HelpCommand(HELP_CONTEXT,100)    else     Messagedlg('Cannot load help file'); end; Application.HelpFile fetches the exact address of your chm file. Application.HelpCommand(HELP_CONTEXT,100) loads your ch

Calling Conventions in Delphi: safecall vs stdcall vs cdecl

Calling Conventions in Delphi: safecall vs stdcall vs cdecl Calling conventions in Delphi determine the order in which parameters are passed to the routine. Calling conventions also affect the removal of parameters from the stack, the use of registers for passing parameters, and error and exception handling.  Calling Conventions in Delphi One of the most common operations in the processing of code is calling a subroutine that carries out a given task. In order to do that, the main code needs to hand over control to the subroutine, allow the subroutine to execute, and then return to where it left the main execution path. This process requires agreement between the caller and the callee about how to pass information to the subroutine, how to return results where applicable and who is responsible for the memory allocation and cleanup. Various conventions exist to deal with invoking subroutines, commonly known as calling conventions. Calling conventions in Delphi define a number of differe

Devexpress vs Telerik vs Infragistics: Which one to choose and why?

Devexpress vs Telerik vs Infragistics: Which one to choose and why? Devexpress, Telerik and Infragistics are the great third party tools for you for both your windows and web application. These third party tools mainly support .NET technologies like WinForms, Silverlight, ASP.NET and WPF. Devexpress also supports windows application built in  Delphi programming language and I am currenty working on it. Also I have heard some other third party tools like ComponentOne, SyncFusion and Januscontrols but never worked upon them. Which one is good, which one to choose and why? Although this is difficult and time consuming task, but let's try to solve the confusion. Why do we require these third party tools for our application? These all thrid party tools are mainly used for improving the user interface which standard controls cannot provide. Devexpress, Telerik and Infragistics third party tools provide a lot of exciting features and components which you require like attractive dashboards

MongoDB vs Cassandra: Difference and Similarities between MongoDB and Cassandra

MongoDB vs Cassandra: Difference and Similarities between MongoDB and Cassandra MongoDB and Cassandra have occupied a very big market of NoSQL Schema-Free databases. So, before going to choose any one of them, it is logical to compare basic features of both MongoDB and Cassandra. MongoDB and Cassandra both are fully-featured NoSQL databases and choosing one of them heavily depends upon your application requirements. There are a lot of similarities and differences between MongoDB and Cassandra. Following is the basic comparison of MongoDB and Cassandra in terms of data storage model, usage etc. Differences between MongoDB and Cassandra 1. MongoDB has a document-oriented data model while Cassandra has column-oriented data model and storage type.  MongoDB acts much like a relational database. Its data model consists of a database at the top level, then collections which are like tables in MySQL (for example) and then documents which are contained within the collection, like rows in MySQL

24 Frequently Asked Basic SOA Interview Questions and Answers

24 Frequently Asked Basic SOA Interview Questions and Answers SOA stands for Service Oriented Architecture. If you are preparing for SOA interview, the following SOA interview questions and answers can be very useful to you. Basically, these SOA interview questions and answers cover basic concepts of SOA like services in SOA, characteristics and principles of services in SOA, loose coupling of services, contract, address and bindings in SOA, main benefits of SOA to the business and IT, difference between services and components in SOA, requirement of SOA to the business, pitfalls of SOA etc. Let's have a look: 1. What is a Service in SOA? In the real world, a service is what we pay for and we get the intended service.  Example 1 (from Real World): You go to a restaurant and order food. Your order first goes to the counter and then it goes to the kitchen where the food is prepared and finally the waiter serves the food. So in order to order an item from a restaurant you need three