Updating rows of a table with a UUID column
You can update a UUID column whether or not it is GENERATED BY DEFAULT. You can use
            the function random_uuid to generate a random UUID value to update the
            column. The function random_uuid returns a randomly generated UUID, as
            a string of 36 characters. 
               
Example : Updating a UUID Column defined without GENERATED BY DEFAULT clause
CREATE TABLE myTable (tabId INTEGER, id STRING AS UUID, PRIMARY KEY (tabId));
Statement completed successfully
INSERT INTO myTable values(1,"a81bc81b-dead-4e5d-abff-90865d1e13b1");
Statement completed successfully
UPDATE myTable set id=random_uuid() where tabId=1;
Statement completed successfullyThe above example shows how you can update a UUID column which is NOT GENERATED BY
            DEFAULT. To do so, the UUID column should not be part of the primary key, as NoSQL
            Primary key values are immutable. In the above example, tabId  is the
            Primary key. So you can update the UUID column using the  random_uuid
            function.