Markus Winand

Teaching is about making students reach the same level of understanding as the teacher—but with less mental effort. This allows students to put their mental efforts into growing beyond their teachers.

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Order-equivalent OVER clauses modern-sql.com/blog/2026-03/o… About an important but rarely appreciated aspect when using multiple OVER clauses in a single query.

@Sa07Sanel @slideshare Link: slideshare.net/slideshow/p2d2… ;)

Pagination Done the Right Way by @MarkusWinand via @Slideshare

SQL Comments, Please! modern-sql.com/caniuse/commen… Standard SQL offers two flairs of comments: one starts by two dashes (--) and goes to the end of the line. The other starts with slash-asterisk (/*) and ends with asterisk-slash (*/). #SQL #DuckDB #PostgreSQL #MSSQL

Infinite Recursion Guards modern-sql.com/caniuse/with_r… With recursive is the only SQL construct that is not guaranteed to terminate, eventually. As the DBMS is typically a very crucial system, infinite loops must be prevented at all times. See how various SQL systems help you.

I’m a simple man. While Oracle people are ecstatic about ASSERTION in the just released version 23.26.1 of the Oracle Database, I’m happy to see something as simple as FILTER :) 🧵

Oh, BTW, I’m also ecstatic about ASSERTION, but I’ll need some time to cover it on modern-sql.com.

FILTER was the first feature I covered on modern-sql.com, only supported by PostgreSQL at the time. Today, half the system I cover support FILTER. I cannot understand why there are still systems not support such a simple, easy to understand and useful feature.

Database management is more than persistence A DBMS also provides access rights (GRANT), schema enforcement (types, constraints), schema evolution (ALTER), concurrency control (TX isolation, …), a query language… Persistence = simple DB managemant = hard

Adieu Apache Derby, Welcome DuckDB modern-sql.com/blog/2025-12/d…

modern-sql.com now covers DuckDB.

Another look into PostgreSQL CTE materialization and non-idempotent subqueries shayon.dev/post/2025/124/…

GROUP BY ALL Very popular, not yet standard but set to become standard. Also expected for PostgreSQL 19. modern-sql.com/caniuse/group-…

At least it's not dying without notice: Apache Derby is retired. issues.apache.org/jira/browse/DE… Below: Poll if people would miss Derby on modern-sql.com (not even a year ago).

@ryanguill There is a logical processing sequence (engines might mix that up as long as the result is as though it would have observed this sequence): WHERE -> GROUP BY -> HAVING (uses the result of GROUP BY) -> WINDOW -> QUALIFY (uses the result of WINDOW !!!).

@MarkusWinand duckdb also supports qualify, its very useful. intelectually curious why `having` couldnt be expanded to support window functions rather than needing a new keyword though

Oracle 26ai¹ was released yesterday. Noteworthy SQL addition: QUALIFY. modern-sql.com/caniuse/qualify I bet this starts an avalanche (there are already PostgreSQL patches). ¹ 26ai is the marketing version, 23.26.0 is the technical version.

@SagarDua297 I don't trust the docs. All my charts are bases on actual tests.

@MarkusWinand I don't remember this was in 23ai new features list. Was it added in 26ai doc update? Thanks!

@artur_formella That would be an earlier step of processing — in particular, before WINDOW. Sounds like a different beast. For what do you need that?

@MarkusWinand We need it with JOIN i.e. JOIN X ON Y QUALIFY ONCE PER id

My favorite change is that MariaDB got an improved "WHERE year(...) = ?" rewriting. use-the-index-luke.com/blog/2024-12/d… In picture: the green check mark used to be yellow, with the "a" footnote: Unconditionally rewritten—even if only a matching function-based index exists

After being « gone fishin' » during summertime I just updated my website for the releases that happened during that time: * MariaDB 11.8 and 12.0 * Oracle 23.9 * Db2 12.1.2 All charts on modern-sql.com and use-the-index-luke.com are updated.