Archive - Alexander Obregon's Substack

Weekly Recap – June 15th, 2025

SQL, Kotlin, Java Basics, Spring Boot, and JavaScript

Jun 15 •

Alexander Obregon

Build a Search Feature with SQL LIKE and Wildcards

How Wildcards Shape Your Queries

Jun 13 •

Alexander Obregon

Turning Rows Into Columns To Build Pivot Tables In SQL

When you need to build a report from relational data, the default layout isn’t always what works best.

Jun 13 •

Alexander Obregon

Calculating Percent Change Between Rows in SQL

When working with time-based data or data sorted in a specific order, you often need to compare each value to the one before it.

Jun 11 •

Alexander Obregon

Breaking Big Queries into Manageable Parts with CTEs

Use CTEs to organize your SQL without nesting everything

Jun 10 •

Alexander Obregon

Kotlin Enum Classes and the Companion JVM Code

What the compiler adds to enum classes

Jun 9 •

Alexander Obregon

Weekly Recap – June 8th, 2025

Java, Spring Boot, JavaScript, Kotlin, and LeetCode

Jun 8 •

Alexander Obregon

LeetCode #11: Container With Most Water — Solved in Java

Brute Force and Two-Pointer Solution

Jun 6 •

Alexander Obregon

Working with JavaScript's PerformanceObserver to Track Web Vitals

See what the browser sees and catch layout shifts as they happen

Jun 5 •

Alexander Obregon

How JavaScript String.raw Lets You Handle Escape Sequences Directly

Preserve Backslashes and Escape Sequences Without Guesswork

Jun 5 •

Alexander Obregon

LeetCode #10: Regular Expression Matching — Solved in Java

Recursive Match with Conditions and Dynamic Programming with a 2D Table

Jun 3 •

Alexander Obregon

LeetCode #9: Palindrome Number — Solved in Java

Convert to String and Use Two Pointers and Reverse Half of the Number

Jun 3 •

Alexander Obregon

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