Question

Oracle:-
I have around 850 records in an table, that need to be assigned UUID.

I am using the following query.

select substr(sys_guid(),1,3)||'-'||
          substr(sys_guid(),4,4)||'-'||
          substr(sys_guid(),8,4)||'-'||
          substr(sys_guid(),13)
from (select sys_guid() as mygid from dual)

I need to generate multiple/850 records in one go.
Any suggestions ?
Should I loop over?

Answer 1

If you really need select, use hierarchical query:

SELECT Substr(mygid,1,3)||'-'||
       Substr(mygid,4,4)||'-'||
       Substr(mygid,8,4)||'-'||
       Substr(mygid,12)
  FROM (
        SELECT Sys_GUID() AS mygid FROM dual
        CONNECT BY Level <= :desired_number_of_records
       )   

But what’s wrong with usual update ?

UPDATE your_tab
   SET gid_col = (
         SELECT Substr(mygid,1,3)||'-'||
                Substr(mygid,4,4)||'-'||
                Substr(mygid,8,4)||'-'||
                Substr(mygid,12)
           FROM( SELECT Sys_Guid() AS mygid FROM dual ) 
         )