Python & SQL Tutorials
In-depth tutorials written by Ameer Abdullah, Data Science & AI/ML graduate. Each article explains not just what the code does, but why, building the mental model you need for technical interviews.
Written by Ameer Abdullah
Data Science Graduate · AI/ML & Data Science Domain · Creator of PyCodeIt
Python Tutorials
8 articlesHow to Crack a Tech Interview Using a Trace Table
A step-by-step method for predicting Python output under pressure - without running code.
6 min5 Common Python String Slicing Tricks Interviewers Love
Negative indices, step sizes, and reversals - master the patterns that show up in trace questions.
5 minWhy Dry-Running Beats Memorizing LeetCode Patterns
Pattern decks fail when interviewers change types, side effects, or control flow.
5 minReading Python List Comprehensions Line by Line
Desugar comprehensions into nested loops before you predict output.
6 minDefault Mutable Arguments: The Classic Interview Trap
Why def f(lst=[]) causes shared state - and how to spot it in a trace.
5 minHow to Explain Your Thinking in a 45-Minute Phone Screen
Structure your narration so interviewers can follow your trace table aloud.
6 minRecursion Trace Tables: From Base Case to Return Value
Stack frames make recursion traceable once you tabulate calls and returns.
6 minPython Dictionary Iteration Order and Pitfalls
Insertion order, views, and runtime mutations - common dry-run themes.
5 min
SQL Tutorials
5 articlesSQL Joins Explained for Technical Interview Candidates
Inner, left, right, and full outer joins - understand what rows survive and why before your next data round.
6 minWindow Functions in SQL: RANK, ROW_NUMBER, and LEAD Explained
Aggregate without collapsing rows - the core skill data engineers and analysts get tested on.
7 minCTEs vs Subqueries: When to Use Each and Why It Matters
Common Table Expressions improve readability but the performance story is more nuanced than most articles admit.
6 minGROUP BY and HAVING: The Misconceptions That Cause Wrong Answers
Understanding what each clause filters and when to use WHERE versus HAVING prevents the most common SQL mistakes.
6 minWhat Every Developer Should Know About SQL Indexes in Interviews
B-tree indexes, composite index column order, and when a full table scan is actually faster.
7 min
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