Class 12 Computer Science Notes

Revision of Class 11 Python for Class 12: tokens, variables, data types, mutable and immutable types, operators and expressions, input/output, conditional statements, loops, and break, continue and loop-else, with board-style examples.

Revision of Python strings, lists, tuples and dictionaries — indexing, slicing, operators, built-in functions and methods — with diagrams, common errors and board-style questions.

Defining and calling functions in Python, flow of execution, parameters and arguments (positional, default, keyword), return values, scope of variables and the LEGB rule, and passing mutable and immutable objects, with board-style questions.

Exceptions in Python: syntax errors vs exceptions, common built-in exceptions, and handling them with try, except, else and finally, with programs and board-style questions.

Text files in Python: opening and closing files, file modes, the with statement, read(), readline(), readlines(), write() and writelines(), flush(), file pointers with seek() and tell(), and the standard input, output and error streams.

Binary and CSV files in Python: pickling with dump() and load(), searching, updating and deleting records in a binary file, and reading and writing CSV files with the csv module, including DictReader and DictWriter.

The stack data structure: LIFO, stack terminology (TOP, PUSH, POP, PEEK, overflow, underflow), implementing a stack with a Python list, algorithms for each operation, a menu-driven stack program and applications of stacks.

Computer networks: types of networks (PAN, LAN, MAN, WAN), evolution of networking, circuit and packet switching, data communication terms, guided and unguided transmission media, network topologies, and identifying nodes with MAC and IP addresses (IPv4 and IPv6).

Network devices (modem, NIC, hub, switch, repeater, bridge, router, gateway), network protocols (HTTP, FTP, TCP/IP, PPP, email protocols, VoIP, Telnet), and internetworking concepts: WWW, URLs, DNS, web hosting, HTML, XML and network protection.

Relational databases: purpose of a DBMS, the relational data model and its terminology (relation, tuple, attribute, domain, degree, cardinality), keys (primary, candidate, alternate, foreign), and an introduction to MySQL and SQL.

Writing SQL queries in MySQL: literals, data types, NULL values and comments, SELECT with DISTINCT, calculations and column aliases, the WHERE clause with relational, logical, BETWEEN, IN, LIKE and IS NULL conditions, ORDER BY, MySQL functions and aggregate functions.

Creating databases and tables in MySQL, SQL constraints, DML commands (INSERT, UPDATE, DELETE), and further DDL commands such as ALTER TABLE and DROP TABLE, with example queries.

Types of SQL functions, grouping rows with GROUP BY, filtering groups with HAVING, and combining tables with joins — Cartesian product, Equi-Join and Natural Join — with example queries.

Connecting Python to MySQL with mysql.connector: creating a connection and cursor, running SELECT queries with fetchall(), fetchone() and fetchmany(), parameterised queries, and INSERT and UPDATE with commit().