1. Why is Python needed?
Python is a general-purpose and 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 Python code 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.
2. What is Python used for?
Python could be used in
- Game development
- Web development
- Artificial Intelligence and Machine Learning
- Desktop GUI
- Image processing
- Graphic design applications
3. What are the key features of Python?
Some of the key features of Python are -
Easy to Read and Understand: Python emphasizes code readability and uses a clean and consistent syntax.
Simple and Expressive Syntax: Python's syntax is designed to be simple and expressive, allowing developers to write code in fewer lines.
Dynamically Typed: Python is a dynamically typed language, which means variable types are determined at runtime.
Strong Standard Library: Python comes with a vast standard library that provides a wide range of functionalities, including file handling, networking, regular expressions, and more.
Cross-Platform Compatibility: Python is a cross-platform language, meaning it can run on different operating systems such as Windows, macOS, and Linux without the need for extensive modifications.
Object-Oriented Programming (OOP) Support: Python supports object-oriented programming principles, allowing developers to create reusable and modular code.
Integration and Extensibility: Python can easily integrate with other programming languages such as C, C++, and Java, enabling developers to leverage existing code and libraries written in different languages.
4. How is memory managed in Python?
The memory is managed by Python's 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's memory manager is responsible for the allocation of heap space for Python objects. The core API then gives access to a few tools for the programmer to code.
It also consists of an integrated garbage collector that recycles unused memory and makes it available to heap space.
5. What are modules in Python?
Python modules 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:
- os
- sys
- math
- random
- datetime
- JSON
6. Explain the namespace in Python.
In Python, a namespace is a container that holds a set of names (identifiers) and their corresponding objects. It provides a way to organize and manage names in a program, avoiding naming conflicts and providing a logical structure for accessing variables, functions, and classes.
A Python statement can access variables in a local as well as a global namespace. If a local and a global variable have the same name, then the local variable shadows the global variable.
7. What is a dictionary in Python?
A dictionary in Python is the built-in data type. It 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.
Example:
Input:
capital_city = {
"Nepal": "Kathmandu",
"Italy": "Rome",
"England": "London"
}
print(capital_city)
Output:
{
'Nepal': 'Kathmandu',
'Italy': 'Rome',
'England': 'London'
}
8. Differentiate between xrange and range in Python.
Both are identical in terms of functionality. The only difference between the two is that xrange produces an xrange object whereas range provides a Python list object.
Unlike range, xrange does not create a static list during execution. It generates the values according to the need through yielding techniques. Yielding helps in employing Generators (a type of object). You should use xrange when you have a large range and you want to construct a list for billions of people.
This is important for systems that demand a lot of memory since range will utilise as much RAM as it can for building your array of numbers. This will cause a memory problem and crash your app.
9. What is the use of DBMS?
Database Management System (DBMS) is an application system wherein the main purpose is to revolve around data. This allows the user to store the data, define it, retrieve it and update the information about the data inside the database.
10. What do you mean by Database?
Database refers to a collection of data in some organized way to facilitate its users to easily access, manage and upload the data.
11. Why is it recommended to use a DBMS? List four major advantages of using a DBMS.
Reduces Data Redundancy: DBMS supports a mechanism to reduce the data redundancy inside the database by integrating all the data into a single database and as data is stored in only one place, the duplicity of data does not happen.
Data Sharing: Sharing data among multiple users can be done simultaneously in DBMS as the same database will also be shared among all the users and by different application programs.
Data Integrity: This means that the data is always accurate and consistent in the database. It is very important as there are multiple databases in a DBMS and all of these databases contain data that happens to be visible to multiple users. So it is vital to ensure that the data is correct and consistent in all the databases and for all the users.
Data Security: In data security, only authorised users are allowed to access the database and their identity should be authenticated using a valid username and password. Unauthorised users are not allowed to access the database under any circumstances as doing so violates the integrity constraints.
12. Why is normalization needed in DBMS?
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, such as
- To minimize data redundancy.
- To minimize the anomalies of Insert, Delete and Update.
13. Explain the concepts of a Primary key and a Foreign key.
The primary key uniquely identifies the records in a database table while the 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 'Dept ID' where Dept ID is the primary key of the Employee table while this happens to be the foreign key for the Department table.
14. What is the difference between UNION and UNION ALL?
They are both used to join the data from two 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.
15. Explain the concept of ACID properties in DBMS.
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 data amongst multiple users.
Atomicity: When changes are being done to the data it feels as though a single operation is performed. In other words, either all the changes are performed, or none of them is performed.
Consistency: Data must be in a consistent state at the beginning of the transaction as well as at the end of the transaction.
Isolation: As the name suggests, this ensures that each transaction that occurs is in isolation from others. Simply put, a transaction that has started but not yet completed should be in isolation from others, this is done so that the other transaction does not get impacted by this transaction.
Durability: In the event of system failure, after the transaction is completed, changes to the data persist and are not undone. Hence, due to this property, data is always in a durable state.
16. What are Constraints in SQL?
Constraints are used to specify the rules concerning data in the table. It can be applied for single or multiple fields in an SQL table during the creation of the table or after creating using the ALTER TABLE command. The constraints are:
- NOT NULL - Restricts NULL value from being inserted into a column.
- CHECK - Verifies that all values in a field satisfy a condition.
- DEFAULT - Automatically assigns a default value if no value has been specified for the field.
- UNIQUE - Ensures unique values to be inserted into the field.
- INDEX - Indexes a field providing faster retrieval of records.
- PRIMARY KEY - Uniquely identifies each record in a table.
- FOREIGN KEY - Ensures referential integrity for a record in another table.
17. What is Data Integrity?
Data Integrity is the assurance of accuracy and consistency of data over its entire life-cycle and is a critical aspect of the design, implementation, and usage of any system which stores, processes, or retrieves data. It also defines integrity constraints to enforce business rules on the data when it is entered into an application or a database.
