uuidgen for sqlite

uuidgen.sql

/* uuidgen.sql
 * 
 * creates a view uuidgen(uuid TEXT) which generates v4 UUIDs on demand
 *   generated per RFC 4122
 *
 * it's not a stored procedure exactly but subqueries are allowed in
 *   any expression
**/
CREATE VIEW uuidgen AS 
SELECT printf('%x-%x-%x-%x-%x', 
              random() & 0xffffffff, 
              random() & 0xffff, 
              random() & 0x0fff | 0x4000, -- version 4, random uuid
              random() & 0x3fff | 0x8000, -- variant 1, RFC 4122 uuid
              random() & 0xffffffffffff) 
              AS uuid;