Class 12 Computer Science

Writing your own functions, arguments and parameters, default and positional, returning values, and why a variable inside a function is invisible outside it.

try, except and finally — catching the error you expected without swallowing the one you did not.

Open modes r through a+, the with clause, read/readline/readlines, write and writelines, and what seek and tell actually count.

pickle dump and load, the rb/wb/ab modes, and doing search, append and update on records that are not text.

The csv module, writer/writerow/writerows and reader — and why newline= matters more than any tutorial admits.

Last in, first out, implemented on a plain Python list — push, pop, and the empty-stack case that separates a working implementation from a crashing one.

ARPANET to the internet, the five components of data communication, bandwidth versus data transfer rate, IP addresses, and circuit versus packet switching.

Twisted pair, co-axial and fibre, radio, micro and infrared waves — and what a hub, switch, router, repeater and gateway each actually do.

PAN through WAN, bus star and tree, the protocol list the exam names, and WWW, HTML, XML, URLs, web servers and hosting.

Why a database beats a pile of files, then relation, attribute, tuple, domain, degree, cardinality — and candidate, primary, alternate and foreign keys.

DDL and DML, data types and constraints, create through drop, insert, select, where, in, between, like, order by — and what NULL really means.

max, min, avg, sum and count, group by and having, then cartesian product, equi-join and natural join — and why COUNT(*) and COUNT(column) disagree.

connect, cursor, execute, commit, fetchone, fetchall and rowcount — running real queries from Python, and why the %s placeholder is not string formatting.