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10. MySQL Part 1: Install, Create, Insert and SELECT

10.4 Inserting Data

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INSERT INTO students (name, email, city, age, fees_paid, joined_on) VALUES
 ('Ravindra Bagale', 'ravindra@example.com', 'Pune',         NULL, 15000, '2026-01-05'),
 ('Shraddha Bagale', 'shraddha@example.com', 'Pune',           29, 15000, '2026-01-05'),
 ('Ruhi Bagale',     'ruhi@example.com',     'Nashik',         21, 12000, '2026-02-10'),
 ('Shahrukh',        'shahrukh@example.com', 'Nagpur',         24,  8000, '2026-02-15'),
 ('Amir',            'amir@example.com',     'Kolhapur',       26, 15000, '2026-03-01'),
 ('Salman',          'salman@example.com',   'Solapur',        23,     0, '2026-03-03'),
 ('Zoya',            'zoya@example.com',     'Sambhaji Nagar', 22, 10000, '2026-03-20'),
 ('Ravina',          'ravina@example.com',   'Nagpur',         25, 12000, '2026-04-02'),
 ('Raja',            NULL,                   'Nashik',         20,  5000, '2026-04-11'),
 ('Rani',            'rani@example.com',     'Pune',           27, 15000, '2026-04-18');

INSERT INTO courses (course_name, duration_wk) VALUES
 ('Networking', 4), ('Linux', 6), ('AWS', 8), ('Ethical Hacking', 10), ('SOC Analyst', 6), ('Cloud Security', 6);

INSERT INTO enrollments (student_id, course_id, score) VALUES
 (1,1,92),(1,4,88),(2,2,79),(3,1,65),(3,2,71),(4,4,58),(5,3,84),
 (6,1,45),(7,5,90),(8,4,76),(8,5,81),(10,3,67);

SELECT COUNT(*) FROM students;     -- 10

Student 9 (Raja) is deliberately in no course, course 2 (Linux) has two students and course 6 (Cloud Security) has none – we will need these for JOINs. Ravindra's age is left NULL on purpose for the NULL examples.

Why this matters for security

Every INSERT built from user input must use prepared statements (section 9.7). A value like '), ('hacker','x inside a string-concatenated INSERT can add extra rows or break the query – that is SQL injection in an INSERT.

Ravindra Bagale's Tip

Many students write INSERT INTO students VALUES (...) without a column list – then when a column is added later, the query breaks. Always write the column names. And put text in single quotes, like 'Pune', and numbers without quotes.

Practice task

Insert the sample data exactly as shown, then add yourself as a new student and one new course of your choice.

Extended teaching notes

Why this lesson matters

Use this lesson to strengthen systems you own: understand the risk, practise safely in a lab, then write and apply the fix.

Apply the fix across stacks

Same class of bug, same idea in every language.

Java / Spring Boot

Parameterise queries, encode output, CSRF tokens, limited Actuator, dependency scanning.

ASP.NET Core

EF Core / parameterised SQL, Razor encoding, HTTPS, Data Protection.

Node.js / Express

helmet, parameterised SQL, npm audit, avoid eval and shell concat.

Python / Django / Flask / FastAPI

ORM, autoescape, pip-audit, Bandit; never shell=True with user input.

PHP / Laravel

PDO/Eloquent, Blade escaping, composer audit.

Go / Ruby

database/sql placeholders / ActiveRecord; html/template / ERB escaping; govulncheck / Brakeman.

nginx / Apache / Tomcat

Hide versions, TLS, security headers, least-open ports.

MySQL / PostgreSQL / MongoDB / Redis

Private networks, auth on, least-privilege users, no 0.0.0.0/0.

AWS / Azure / GCP

Roles not long-lived keys, private data stores, cloud audit logs on.

Mini case study

Suppose we are on a purple-team exercise for an Indian mid-size company (sample data). Red notes a technique from this lesson against a lab clone. Blue must show the control that stops it, the log that would have fired, and the ticket that hardens production. That is the standard this course trains you for.

Defender's worksheet (do this today)

  1. Write the lesson title, date and the exact lab target you are allowed to use.
  2. List three owned systems (VMs, apps, or cloud accounts) where this lesson applies.
  3. Run one safe check from the lesson on a lab system only. Paste the command and output.
  4. Write a two-sentence fix you would give a teammate.
  5. Name one related public advisory (CERT-In, CISA, NVD, or a vendor bulletin) with its date.

Indian workplace (sample data)

Suppose we are a junior analyst at Infosys, TCS, Wipro or a fintech SOC in Bengaluru/Pune. Turn this lesson into one checklist item with an owner, a due date and a place to store evidence (ticket + screenshot).

Global practice

Compare your notes with OWASP, CIS Benchmarks, NIST CSF/IR guidance or a cloud Well-Architected security question. Write five lines on what overlaps.

Everyday analogy

Explain the risk and the fix to a family member without jargon. If they can repeat the warning, you understand it well enough to teach juniors.

Key terms

  • Control: a safeguard (patch, config, process, detection).
  • Finding: a weakness backed by evidence.
  • Remediation: the fix plus how you verified it.
  • Scope: systems you have written permission to touch.
  • Least privilege: only the access the task needs.
  • Defence in depth: several layers so one failure does not end the story.

Common mistakes

  • Skipping written permission "just for a quick scan".
  • Practising on hostel, office or public targets without authorisation.
  • Collecting tool output without writing the fix.
  • Copying attack steps onto production to "verify". Defenders verify with versions, configs and patches.
  • Publishing screenshots that contain secrets, cookies or internal hostnames.

Recap

  • Evidence, fix, owner, date.
  • Own lab only.
  • Fix > spectacle.