GUID

The GUID group works with Delphi TGuid records and common textual representations. Use it to create a Windows UUID, represent the all-zero sentinel, parse supplied text or convert an identifier for a filename, display field or legacy SQL fragment.

Common tasks

• Use NewGuid when a TGuid record is required, or the NewGuidString... entries for the exact documented text form.
• Use EmptyGuid, EmptyGuidString and IsEmptyGuid for the all-zero sentinel.
• Use SafeStringToGuid for its specific empty/bracing behavior, not as a general validation promise.
• Use GUIDToStringNoBraces when a canonical 36-character hyphenated form without braces is required.

Representation rules

A GUID record and a GUID string are different types. Text can include or omit braces and has a defined hyphen layout and hexadecimal case on the output paths. Compare identifiers as TGuid values or as one canonical text representation; do not compare a mixture of optional braces and arbitrary casing.

The all-zero GUID is a conventional sentinel in many Velox contracts, not SQL NULL and not an absent Variant. Check the owning module or database column's meaning before translating between them.

Important behaviour and quirks

Creation delegates to Windows, but the current helper family does not uniformly surface the operating-system status. A generated value is intended to be practically unique; it is not proof of authorization, secrecy, ordering or successful persistence.

NoBraces is a text helper with deliberately weak validation: an opening brace can cause first/last-character removal without proving the content is a GUID or even has a closing brace. SafeStringToGuid also has exact brace-detection and empty-input rules described on its page; malformed non-empty input can still raise.

GUIDToSQL produces a quoted literal fragment. It does not bind a parameter, escape arbitrary surrounding SQL or implement database null semantics. Prefer typed parameters when possible.