SQL · Theory

Introduction

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Introduction

Don’t start Introduction with jargon. Start with a students table. That is the whole point.

Introduction order — meaning → SELECT name FROM students → one limit. Dumping ten features helps nobody.

Introduction exists so Riya can keep a students table correct in a college DB.

Introduction shows up in a college DB. Name a students table, not “a real-world scenario”.

If a students table breaks under Introduction, check calling SQL a programming language like Java first.

Place Introduction next to nearby SQL work — SELECT name FROM students is the link.

Viva for Introduction: what it is → SELECT name FROM students → the mistake (calling SQL a programming language like Java).

Exam tip

Board: a students table. Dry-run Introduction. Name the trap: calling SQL a programming language like Java.

Introduction — sample query

-- Introduction
CREATE TABLE demo (
  id INTEGER PRIMARY KEY,
  label TEXT NOT NULL,
  qty INTEGER DEFAULT 0
);
INSERT INTO demo (id, label, qty) VALUES
  (1, 'alpha', 2),
  (2, 'beta', 5);
SELECT label, qty FROM demo WHERE qty >= 2 ORDER BY qty DESC;

Introduction: create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Short notes

DefIntroduction — Riya uses it for a students table in a college DB.
RuleIntroduction → SELECT name FROM students.
RememberIntroduction + an index (a college DB).
UseIntroduction in a college DB (a students table).
TrapIntroduction — calling SQL a programming language like Java.
ExIntroduction → a students table.

-- Introduction CREATE TABLE demo ( id INTEGER PRIMARY KEY, label TEXT NOT NULL, qty INTEGER DEFAULT 0 ); INSERT INTO demo (id, label, qty) VALUES (1, 'alpha', 2), (2, 'beta', 5); SELECT label, qty FROM demo WHERE qty >= 2 ORDER BY qty DESC;

Introduction

Introduction — sample query

Short notes

Questions

Introduction

Introduction — sample query

Short notes

Questions