Beginner Notes - Page 8

DELETE and Safe Data Modification

DELETE removes rows permanently. Learn targeted deletes, deleting through a join, soft deletes and the habits that stop a one line mistake becoming an...

SQL

UPDATE: Conditional and Multi Column Changes

UPDATE changes existing rows. Learn multi column updates, conditional logic with CASE, updates driven by a join and how to check the blast radius firs...

SQL

INSERT: Single Row, Multi Row and INSERT SELECT

Every way to put rows into a table: explicit column lists, multi row VALUES, INSERT ... SELECT, defaults and handling duplicate keys.

HTML

Emphasis and Importance: strong, em, b and i

Four elements, two that look bold and two that look italic, and the pairs are not interchangeable. The difference is meaning, and screen readers act o...

SQL

DROP, TRUNCATE and DELETE Compared

Three ways to remove data, with very different consequences. Learn what each one destroys, what can be rolled back and what resets identity counters.

HTML

Paragraphs, Line Breaks and Thematic Breaks

The p element is the workhorse of body copy. br and hr look like spacing tools but are content, and using them for layout is the most common beginner...

HTML

Headings h1 to h6 and the Document Outline

Headings are the table of contents of your page. Choose the level from where the section sits in the outline, never from how big the text should look.

SQL

CREATE: Databases, Schemas and Tables

CREATE defines the objects data lives in. Learn CREATE DATABASE, CREATE SCHEMA and CREATE TABLE, with column definitions and inline constraints.

SQL

The Sample Database Used in This Path

Two small schemas - a company HR database and a shop sales database - used by every example in this SQL path. Create them once and follow along.

HTML

Writing and Running Your First HTML Page

Set up a folder, save a real .html file, open it in a browser and understand the difference between opening a file and serving it. The workflow every...

SQL

SQL Operators and Expressions

Arithmetic, comparison, logical, string and set operators, how precedence works, and where an expression may legally appear.

HTML

Block Level and Inline Elements

The oldest distinction in HTML layout: block boxes stack down the page and fill the width, inline boxes sit inside a line of text. It also decides whi...