Beginner terms
MySQL ENUM Type
A column that accepts only predefined string values — stored efficiently as integers but with significant schema change pain.
6mo ago
Database beginner
MySQL JOIN Types
INNER JOIN, LEFT JOIN, RIGHT JOIN, and CROSS JOIN — controlling which rows are included when combining tables.
6mo ago
Database beginner
MySQL NULL Handling
NULL in SQL represents an unknown value — it is not zero, not empty string, and comparisons with = NULL are always false.
6mo ago
Database beginner
MySQL Numeric Types
INT, BIGINT, DECIMAL, FLOAT, DOUBLE — the right type prevents overflow, precision loss, and money calculation bugs.
6mo ago
Database beginner
MySQL String Types: VARCHAR vs TEXT vs CHAR
CHAR is fixed-length, VARCHAR is variable-length up to 65,535 bytes, TEXT variants store large content — each with different indexing and storage behaviour.
6mo ago
Database beginner
PDO Error Handling
PHP 5.1+
PDO has three error modes — silent, warning, and exception — controlling how database errors surface.
6mo ago
PHP beginner
PDO Fetch Modes
PHP 5.1+
Constants controlling how PDO returns rows — as arrays, objects, or custom classes.
6mo ago
PHP beginner
PDO lastInsertId()
PHP 5.1+
Returns the auto-increment ID generated by the most recent INSERT statement.
6mo ago
PHP beginner
PDO Named Placeholders
PHP 5.1+
Named parameters (:name) in prepared statements — more readable than positional ? placeholders for queries with multiple parameters.
6mo ago
PHP beginner
PDO query() vs prepare()
PHP 5.1+
PDO query() executes raw SQL immediately — prepare() parameterises it. query() must never include user-controlled values.
CWE-89 OWASP A3:2021
6mo ago
PHP beginner
9.8
PDOStatement::rowCount()
PHP 5.1+
Returns the number of rows affected by the last DELETE, INSERT, or UPDATE — unreliable for SELECT.
6mo ago
PHP beginner
Accessible Data Tables
HTML tables marked up with correct semantic elements and ARIA roles so screen readers can announce cell context — column header, row header, and position — to the user.
6mo ago
Accessibility beginner
CSS Grid Template Areas
1
A CSS Grid feature that lets you name regions of a grid and assign elements to them by name, making complex layouts readable and maintainable without calculating column/row numbers.
6mo ago
Frontend beginner
prefers-reduced-motion — Accessible Animations
A CSS media query and JavaScript API that detects when a user has requested reduced motion in their OS settings, allowing you to disable or simplify animations that can trigger vestibular disorders.
6mo ago
Accessibility beginner
Anchors & Word Boundaries
PHP 5.3+
3
Zero-width assertions that match positions rather than characters — ^ matches start of string, $ matches end, \b matches a word boundary — ensuring patterns match in the correct location.
6mo ago
Regex beginner
Array.flat() & Array.flatMap()
ES2019
1
Array.flat(depth) flattens nested arrays; Array.flatMap() maps then flattens one level — more efficient than map().flat() and great for expanding items.
6mo ago
JavaScript beginner
array_column() — Plucking Values from Arrays
PHP 5.5+
array_column() extracts a single column from a multi-dimensional array or array of objects — the idiomatic PHP replacement for foreach loops that build lookup arrays, and for creating ID-indexed maps.
6mo ago
PHP beginner
array_find() / array_find_key() (PHP 8.4)
PHP 8.4+
4
PHP 8.4 adds array_find() and array_find_key() — built-in functions that return the first element (or key) matching a callback predicate, replacing verbose foreach loops or array_filter() + reset() patterns.
6mo ago
PHP beginner
Arrow Functions fn() => (PHP 7.4)
PHP 7.4+
PHP 7.4 arrow functions (fn($x) => $x * $factor) are short closures that automatically capture outer scope — no more use($var) boilerplate.
6mo ago
PHP beginner
Capture Groups & Backreferences
PHP 5.3+
5
Parentheses in a regex pattern create capture groups that store matched substrings for extraction or reuse — backreferences let you match the same text again later in the pattern or replacement string.
6mo ago
Regex beginner