Cheat Sheets

• SQL Cheat Sheet
  A quick reference for SQL clause order, JOIN types, aggregate functions, and common string/date functions.
• Regex Cheat Sheet
  A quick reference for regex character classes, anchors, quantifiers, groups, flags, and a handful of common patterns.
• Cron Syntax Cheat Sheet
  A quick reference for cron field order and ranges, special characters, shortcut expressions, and common example schedules.
• cURL Flags Cheat Sheet
  A quick reference for the most commonly used cURL flags, each with a one-line meaning and a small usage example.
• JWT Claims Cheat Sheet
  A quick reference for the standard registered JWT claims, common custom claims, and why JWT payloads are readable by anyone with the token.