Time zones and UTC handling

Concepts covered: sqlTimezones

Time zones are one of the most error-prone areas in data engineering. A timestamp without timezone context is ambiguous. Is "2025-03-15 14:00:00" in UTC? Eastern Time? The server's timezone? Incorrect assumptions lead to data shifted by hours, causing wrong aggregations and confused stakeholders. Timezone Best Practices Following these guidelines helps avoid timezone-related bugs in global applications. Always use full IANA timezone names like America/New_York rather than abbreviations like EST, which are ambiguous and do not handle daylight saving transitions. Storing timestamps in UTC and converting to local time at display is the most reliable strategy for global applications. AT TIME ZONE adjusts both the displayed value and the timezone offset, ensuring correct representation across a

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This section is part of the Data Types: Intermediate lesson on DataDriven, a free data engineering interview prep platform. Each section includes explanations, worked examples, and hands-on code challenges that execute in real time. SQL queries run against a live PostgreSQL database. Python runs in a sandboxed Docker container. Data modeling problems validate against interactive schema canvases. All content is framed around what data engineering interviewers actually test at companies like Meta, Google, Amazon, Netflix, Stripe, and Databricks.

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