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Database references and tutorials, with every example run against a real server before it is published.

Every example was runNot copied. Output on these pages came out of a real server, more than once each, so random and clock-dependent results are never printed as if they were fixed.

Four engines alongsideWhere the translation is not obvious, a page says what the same job is called in MySQL, SQL Server, Oracle and SQLite — and which of them will quietly give you a different answer.

Nothing paddedA function gets a page when there is something on it the documentation does not have. The ones we could not improve on do not have pages.

PostgreSQL function reference230 functions — mathematical, string, aggregate, json, array, date/time, window, formatting — with 282 examples verified against PostgreSQL 18.6.SQL Server function reference113 functions — string, mathematical, aggregate, date and time, metadata, analytic, security, ranking, json, system, cryptographic, conversion — with 174 examples verified against SQL Server 16.0.4265.3.