TZSTRING
Canonical RFC-9557 string for a zone-aware instant
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When to use it
When should I use TZSTRING instead of TZTEXT?
Use TZSTRING when you need the full RFC-9557 machine-readable wire format (e.g., for API payloads, database storage, or log pipelines) that includes both the UTC offset and the IANA timezone name. Use TZTEXT when you need a human-readable display string.
What does TZSTRING include that a plain ISO-8601 timestamp does not?
TZSTRING appends the IANA timezone name in brackets (e.g., [America/New_York]) after the UTC offset, making it an RFC-9557 zoned datetime. This lets any RFC-9557-aware parser reconstruct the exact civil time and timezone rules, not just the UTC instant.
Can I round-trip a zoned value through TZSTRING and TZPARSE?
Yes. TZPARSE is the exact inverse of TZSTRING, so TZPARSE(TZSTRING(zoned)) recovers the original zone-aware instant without any loss of timezone information.
Use cases
Log a converted instant in the destination timezone
Store a shift start time as a portable zoned string
Used in
Syntax
TZSTRING(zoned)