DBMS is also known as Database Management System. It is an application system wherein its main purpose is to revolve around data. This allows its user to store the data, define it, retrieve it and update the information about the data inside the database.
Simply put, Database refers collection of data in some organized way to facilitate its user’s to easily access, manage and upload the data.
Normalization is the process of analyzing relational schemas which are based on their respective
functional dependencies and the primary keys so that they fulfill certain properties.
Properties:
Primary Key uniquely identifies the records in a database table while Foreign Key, on the other
hand, is used to link two or more tables together.
Example: Consider 2 tables – Employee and Department. Both have one common field/column as ‘ID’
where ID is the primary key of the Employee table while this happens to be the foreign key for
the Department table.
They are both used to join the data from 2 or more tables but UNION removes duplicate rows and picks the rows which are distinct after combining the data from the tables whereas UNION ALL, unlike UNION, does not remove the duplicate rows, it just picks all the data from the tables.
ACID properties are a combination of Atomicity, Consistency, Isolation, and Durability properties. These properties prove to be very helpful in allowing a safe and secure way of sharing the data amongst multiple users.
| JDK | JRE | JVM |
|---|---|---|
| JDK stands for Java Development Kit | This tool plays an important role in compiling, documenting, and packaging Java programs | JDK consists of JRE + development tool |
| JRE stands for Java Runtime Environment | This refers to a runtime environment where Java bytecode can be executed | JRE happens to be an implementation of the JVM which physically exists |
| JVM stands for Java Virtual Machine | JVM is an abstract machine and it is said to be a specification that provides a run-time environment in which the Java bytecode can be executed | JVM follows three notations: Specification, Implementation, and Runtime Instance |
main() in Java refers to the entry point for any Java program and is always written as public static void main(String[] args).
Yes, Java is platform-independent. This is because for every operating system present a separate
JVM is available which is capable to read the .class file or byte code.
But while JAVA is a platform-independent language, the JVM is platform-dependent. Different JVM
is designed for different OS and the byte code is capable of running on different OS.
A constructor in Java refers to a block of code which is used to initialize an object and it must have the same name as that of the class. Also, a constructor does not have a return type and it is automatically called when an object is created. There are two types of constructors in Java. They are :
final is a special keyword in Java and can be used as a non-access modifier. It could be used in different contexts. They are given below
It refers to a string collection that is stored in heap memory. So, whenever a new object is created, the String pool first checks whether the object is already present in the pool or not, and if it is present then the same reference is returned to the variable. Otherwise, a new object will be created in the String pool and the respective reference will be returned.
In Java, string objects are immutable in nature. This means that once the String object is created its state cannot be modified. So, if you do try to update the value of that object instead of updating the values of that particular object, Java creates a new string object. Java String objects happen to be immutable as String objects are generally cached in the String pool. As the String literals are usually shared between multiple clients, action from one client might affect the rest. By doing so, it enhances the security, caching, synchronization, and performance of the application.
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Scope of a variable refers to the part of the program where the variable may directly be accessible. DO note that in C, all identifiers are lexically (or statically) scoped.
Dangling Pointer could be defined as a pointer that doesn’t point to a valid memory location. Dangling pointers are created when an object is deleted or deallocated, without modifying the value of the pointer, so that the pointer still points to the memory location of the deallocated memory.
A NULL pointer is often used to indicate that the pointer doesn’t point to a valid location. In an ideal situation, we should initialize pointers as NULL if we are not aware of their value at the time of declaration. Also, a pointer must be made NULL when memory pointed by it is deallocated in the middle of a program.
A local static variable could be defined as a variable whose life doesn’t end with a function call where it is declared. Local static variable extends for the lifetime of the complete program. All calls related to the function do share the same copy of local static variables. They can be used to count the number of times a function is called. DO note that initially, static variables get the default value is 0.
Functions happen to be global by default, in C. The static keyword before a function name makes the function static. Access to static functions is restricted to the file where they are declared as compared to the global functions. Therefore, to restrict access to functions, we make them static. By making functions static, they can reuse the same function name in other files.
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Python is a general-purpose and a high-level programming language and you could use Python for developing desktop GUI applications, websites and web applications. It lets you focus on the core functionality of the application by taking care of common programming tasks. The code in Python is easily readable and maintainable. It supports multiple programming paradigms It happens to be compatible with major platforms and systems Most importantly Python does have a very robust standard library
Python could be used in:
Python is an interpreted language. It is dynamically typed Python functions happen to be first-class objects, in other words, they can be assigned to variables, returned from other functions, and passed into functions. Writing the code in Python is quicker but running it is comparatively slower than in other languages It could be used in many spheres of life, such as game development, web applications, automation, and more.
The memory is managed by Python private heap space. All Python objects and data structures are located in a private heap but the programmer does not have access to this private heap. Instead, this is taken care of by the Python interpreter.
Python modules are could be referred to as files containing Python code and this code could
either be function classes or variables. Simply put, a Python module is a .py file containing
executable code.
Given below are some of the commonly used built-in modules:
Variables are the names or identifiers that map to objects. Whereas the namespace is a dictionary of variable names that could also be referred to as keys and their corresponding objects or values. A Python statement can access variables in a local as well as the global namespace. If a local and a global variable have the same name, then the local variable shadows the global variable.
A dictionary in Python is the built-in data type. A dictionary in Python defines a one-to-one relationship between keys and values. They usually do contain a pair of keys and their corresponding values and are indexed by keys.
When C++ allows classes to inherit some of the commonly used states and behaviour from other classes, it is known as inheritance.
C++ could be defined as a computer programming language that is a superset of C wherein additional features are made in the C language.
Yes, we can call C++ as OOPS. Object-Oriented Programming System means that it provides an application of various concepts including data binding, polymorphism, inheritance, and various others.
Volatile is a function that is used to declare whether the particular variable is volatile and thereby directs the compiler to change the variable externally. This way helps in avoiding the compiler optimization on the variable reference.
A storage class in C++ specifically resembles that of life or even the scope of symbols, including the variables, functions, etc. Some of the storage classes in C++ are mutable, auto, static, extern, register, etc.
The ‘this’ pointer could be referred to as a constant pointer that holds the memory address of the current object. It passed off as a hidden argument to all the nonstatic member function calls and is available as a local variable within the body of all the nonstatic functions. The static member functions can be called even without any object, i.e. with the class name, which is why the ‘this’ pointer is not available for them.
At times there is a need for allowing a particular class to access private or protected members of a class and to do so we make use of a friend class, that is capable of accessing the protected as well as the private members of the class in which it is declared as a friend. A friend function, on the other hand, can access private and protected class members. It could either be a global function or a method of some class.
This question is asked to ease the candidate into the actual interview. Here are a few pointers that could help you while answering this.
