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It is two step process,
1. Make the constructor private so that new operator cannot be used to instantiate the class
2. Return an object of the object if not null otherwise create the object and return the same via a method.

1. When a class does not know the class of objects it needs to create, the factory pattern can be utilized.
2. When a class identifies its sub-classes in order to determine which objects should be created, the factory pattern can be utilized. 
3. You can use the factory pattern in programming to construct an object of any of the sub-classes based on the data provided.

Static or early binding is resolved at compile time. Method overloading is an example of static binding.
Dynamic or late or virtual binding is resolved at run time. Method overriding is an example of dynamic binding.

The differences between Abstract Class and Interface are as follows:

Abstract Class:
1) Abstract classes have a default constructor and it is called whenever the concrete subclass is instantiated.
2) It contains Abstract methods as well as Non-Abstract methods.
3) The class which extends the Abstract class shouldn’t require the implementation of all the methods, only Abstract methods need to be implemented in the concrete sub-class.
4) Abstract class contains instance variables.

Interface:
1 )It doesn’t have any constructor and couldn’t be instantiated.
2) The abstract method alone should be declared.
3) Classes that implement the interface should provide the implementation for all the methods.
4) The interface contains only constants.

SQL injection is a method that hackers use to access sensitive information from an organization's database. This application-layer attack is the result of inappropriate coding in our applications, allowing hackers to inject SQL statements into your SQL code. 
The most common cause of SQL Injection is that user input fields allow SQL statements to pass through and directly query the database. ADO.NET Data Services queries are commonly affected by SQL Injection issues.

An entity set that doesn't have sufficient attributes to form a primary key is referred to as a weak entity set. The member of a weak entity set is known as a subordinate entity. Weak entity set does not have a primary key, but we need a mean to differentiate among all those entries in the entity set that depend on one particular strong entity set.

Select SUBSTRING(Name,1,5) as name
from PERSON

Clustered index is used for easy retrieval of data from the database by altering the way that the records are stored. Database sorts out rows by the column which is set to be clustered index.

A non-clustered index does not alter the way it was stored but creates a complete separate object within the table. It point back to the original table rows after searching.

Synthetic events integrate the responses of many native browser events into a single API, ensuring that the events are consistent across browsers. Regardless matter which browser is used to run the program, it remains consistent. preventDefault is a made-up event in this case.

1. getInitialState(): This is executed before the creation of the component.
2. componentDidMount(): Is executed when the component gets rendered and placed on the DOM.
3. shouldComponentUpdate(): Is invoked when a component determines changes to the DOM and returns a “true” or “false” value based on certain conditions.
4. componentDidUpdate(): Is invoked immediately after rendering takes place.
5. componentWillUnmount(): Is invoked immediately before a component is destroyed and unmounted permanently.

There is no defined data type for it. Depending on the business requirement, it can return data of any type. Many HTTP methods, such as GET, POST, and PUT, can return data in a variety of forms, depending on the use case.

1.REST is an architectural pattern used for creating web services. RESTful API is used to implement that pattern.
2. The data format of REST is based on HTTP. The data format of RESTful is based on JSON, HTTP, and Text.
3. Working of URL is based on request and response. Working of RESTful is based on REST applications.
4. REST is more user-friendly and highly adaptable to all business enterprises and IT. RESTful API is too flexible.

Tip 1 : The cross questioning can go intense some time, think before you speak.
Tip 2 : Be open minded and answer whatever you are thinking, in these rounds I feel it is important to have opinion.
Tip 3 : Context of questions can be switched, pay attention to the details. It is okay to ask questions in these round, like what are the projects currently the company is investing, which team you are mentoring. How all is the work environment etc.