https://jamalhansen.com/series/sql-for-python-developers/Recent content in SQL for Python Developers on Jamal Hansenhttps://jamalhansen.com/author.pnghttps://jamalhansen.com/author.pngHugoen-usMon, 01 Jun 2026 00:00:00 +0000https://jamalhansen.com/blog/orm-vs-raw-sql-decision-framework/Mon, 01 Jun 2026 00:00:00 +0000https://jamalhansen.com/blog/orm-vs-raw-sql-decision-framework/It's not either/or. Use ORMs for CRUD and migrations; use raw SQL for analytics and complex queries. A practical decision guide.https://jamalhansen.com/blog/parameterized-queries-and-security/Mon, 25 May 2026 00:00:00 +0000https://jamalhansen.com/blog/parameterized-queries-and-security/String formatting in SQL is dangerous. Learn parameterized queries to keep user input safe and prevent SQL injection attacks.https://jamalhansen.com/blog/python-duckdb-real-etl-patterns/Mon, 18 May 2026 00:00:00 +0000https://jamalhansen.com/blog/python-duckdb-real-etl-patterns/Build a complete pipeline - fetch from an API, load into DuckDB, transform with SQL, export results. A capstone putting it all together.https://jamalhansen.com/blog/optimizing-queries-explain-for-python-developers/Mon, 11 May 2026 00:00:00 +0000https://jamalhansen.com/blog/optimizing-queries-explain-for-python-developers/Read EXPLAIN output to understand why queries are slow. Learn when to add indexes and when to stop worrying about performance.https://jamalhansen.com/blog/modifying-data-safely/Mon, 04 May 2026 00:00:00 +0000https://jamalhansen.com/blog/modifying-data-safely/INSERT, UPDATE, and DELETE with guardrails. Always use WHERE, test with SELECT first, and use transactions to undo mistakes.https://jamalhansen.com/blog/creating-tables-ddl-for-python-devs/Mon, 27 Apr 2026 00:00:00 +0000https://jamalhansen.com/blog/creating-tables-ddl-for-python-devs/Map Python types to SQL types. Learn CREATE TABLE with primary keys, foreign keys, and constraints like NOT NULL and DEFAULT.https://jamalhansen.com/blog/window-functions-the-feature-python-developers-miss-most/Mon, 20 Apr 2026 00:00:00 +0000https://jamalhansen.com/blog/window-functions-the-feature-python-developers-miss-most/Calculate across rows without collapsing them. Running totals, rankings, and row comparisons that GROUP BY can't do.https://jamalhansen.com/blog/null-the-value-that-isnt/Mon, 13 Apr 2026 00:00:00 +0000https://jamalhansen.com/blog/null-the-value-that-isnt/NULL means "unknown," not "empty." Why NULL = NULL isn't true, three-valued logic, and how NULL behaves in WHERE, GROUP BY, JOINs, and subqueries. Master COALESCE and NULLIF.https://jamalhansen.com/blog/ctes-making-your-sql-readable/Mon, 06 Apr 2026 00:00:00 +0000https://jamalhansen.com/blog/ctes-making-your-sql-readable/WITH clauses let you name your subqueries and read top-to-bottom instead of inside-out. Transform nested spaghetti into clean steps.https://jamalhansen.com/blog/subqueries-when-sql-needs-helper-functions/Mon, 30 Mar 2026 00:00:00 +0000https://jamalhansen.com/blog/subqueries-when-sql-needs-helper-functions/Nest queries inside queries, like Python helper functions. Use them in WHERE, SELECT, or FROM to compute intermediate results.https://jamalhansen.com/blog/joins-explained-for-python-developers/Mon, 23 Mar 2026 00:00:00 +0000https://jamalhansen.com/blog/joins-explained-for-python-developers/Connect related tables like looking up values in a Python dictionary. Covers INNER JOIN, LEFT JOIN, and when to use each.https://jamalhansen.com/blog/having-filtering-grouped-results/Mon, 16 Mar 2026 00:00:00 +0000https://jamalhansen.com/blog/having-filtering-grouped-results/WHERE filters rows before grouping; HAVING filters after. Need "only cities with more than 10 customers"? That's HAVING.https://jamalhansen.com/blog/group-by-aggregating-your-data/Mon, 09 Mar 2026 00:00:00 +0000https://jamalhansen.com/blog/group-by-aggregating-your-data/GROUP BY creates buckets and counts them. It's like Python's `collections.Counter` or pandas `groupby()`. Learn COUNT, SUM, AVG, MIN, and MAX.https://jamalhansen.com/blog/where-filtering-your-data/Mon, 02 Mar 2026 00:00:00 +0000https://jamalhansen.com/blog/where-filtering-your-data/Filter rows with conditions, the SQL equivalent of list comprehension `if` clauses. Covers AND/OR, IN, BETWEEN, LIKE patterns, and NULL handling.https://jamalhansen.com/blog/order-by-sorting-your-results/Mon, 23 Feb 2026 00:00:00 +0000https://jamalhansen.com/blog/order-by-sorting-your-results/SQL returns rows in no guaranteed order. Run the same query twice and you might get different results. ORDER BY gives you control, like Python's sorted() with key functions.https://jamalhansen.com/blog/select-choosing-your-columns/Mon, 16 Feb 2026 00:00:00 +0000https://jamalhansen.com/blog/select-choosing-your-columns/SQL's SELECT is more than picking columns. Rename with AS, compute expressions, and use DISTINCT for unique values.https://jamalhansen.com/blog/from-where-your-data-lives/Mon, 09 Feb 2026 00:00:00 +0000https://jamalhansen.com/blog/from-where-your-data-lives/We write SELECT first, but FROM executes first. It's like the `for item in collection` part of a Python loop. You pick your data source before doing anything else.https://jamalhansen.com/blog/sql-thinks-in-sets-not-loops/Mon, 02 Feb 2026 00:00:00 +0000https://jamalhansen.com/blog/sql-thinks-in-sets-not-loops/The mental model shift that makes SQL click: SQL is declarative (describe what you want) rather than procedural (step-by-step loops). Once you think in sets instead of rows, the keywords become intuitive.https://jamalhansen.com/blog/dont-forget-to-save-persisting-your-duckdb-database/Mon, 26 Jan 2026 00:00:00 +0000https://jamalhansen.com/blog/dont-forget-to-save-persisting-your-duckdb-database/Your in-memory database disappears when Python exits. Let's fix that with a one-line change that saves everything to disk.https://jamalhansen.com/blog/generate-practice-data-with-faker/Mon, 19 Jan 2026 00:00:00 +0000https://jamalhansen.com/blog/generate-practice-data-with-faker/Real SQL practice needs real-looking data. Generate hundreds of customers with Python's Faker library without downloading a single CSVhttps://jamalhansen.com/blog/run-your-first-sql-query-in-under-5-minutes/Sat, 10 Jan 2026 00:00:00 +0000https://jamalhansen.com/blog/run-your-first-sql-query-in-under-5-minutes/Install DuckDB with pip, create your first table, insert data, and run a SQL query - all in Python, all in under 5 minutes, zero configuration requiredhttps://jamalhansen.com/blog/i-know-python-why-learn-sql/Mon, 05 Jan 2026 00:00:00 +0000https://jamalhansen.com/blog/i-know-python-why-learn-sql/Learning SQL will make you a better Python developer, even if you already use pandas and ORMs. The first in a series of posts that will walk you through the fundamentals using DuckDB and Python.