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UUID Operations

The UUID type represents 128-bit unique identifiers.

UUID literals​

UUID literals are specified with UUID 'string-literal', where the string literal must have an appropriate shape for a UUID. An example is: UUID '123e4567-e89b-12d3-a456-426655440000'. A literal accepts the same spellings as a cast from a string, described below.

UUID value operations​

UUID values can be cast to strings (VARCHAR or CHAR), producing a string with a representation similar to the one of UUID literals described above.

CHAR or VARCHAR values can be cast to UUID values. The string must hold 32 hex digits of either case, optionally enclosed in braces, and a hyphen may separate any complete group of four digits. All of the following denote the same value:

123e4567-e89b-12d3-a456-426655440000
123E4567-E89B-12D3-A456-426655440000
123e4567e89b12d3a456426655440000
{123e4567-e89b-12d3-a456-426655440000}
123e-4567-e89b-12d3-a456-4266-5544-0000

Any other string causes a runtime error. Blanks are never trimmed, so a leading or trailing blank makes the cast fail, as does the URN form urn:uuid:123e4567-e89b-12d3-a456-426655440000. These rules match PostgreSQL.

UUID values can be cast to BINARY or VARBINARY values, and will produce a 16 byte result.

Conversely, BINARY and VARBINARY values can be cast to UUID values. The value must be exactly 16 bytes; any other length causes a runtime error.

UUID comparisons​

Comparing a UUID with a string or a binary value converts that value to a UUID, the same direction as comparing a string with a number. A value that does not denote a UUID is therefore a runtime error:

UUID '123e4567-e89b-12d3-a456-426655440000' = '123E4567-E89B-12D3-A456-426655440000'  -- true
UUID '123e4567-e89b-12d3-a456-426655440000' = x'123e4567e89b12d3a456426655440000'     -- true
UUID '123e4567-e89b-12d3-a456-426655440000' <> ''                                     -- runtime error

A CHAR(n) value is padded with blanks to n characters, so comparing a UUID with a CHAR(40) value fails, whereas CHAR(36), the exact width of a UUID, leaves nothing to trim.

UUID values can be cast to VARIANT; VARIANT values can be cast to UUID.