How to compare records and assign a value in sqlserver

Question

i have two columns in my database "Name" and "Id"

eg

NAME | ID       
-----+-----------
jhon | 0
-----+-----------
kim  | 0
-----+-----------
alex | 0
-----+-----------
jhon | 0
-----+-----------
alex | 0
-----+-----------
max  | 0
-----+-----------

Currently i have assigned "id" 0 to all. i want to write a stored procedure or query that assign the same id (any random value) to the records that are occurring more than one time. Other record's ID remain 0 . for example john and Alex are occurring twice. so their id should be update else other record's ID remain same . here is my sample and desired out put

NAME | ID       
-----+-----------
jhon | 25
-----+-----------
kim  | 0
-----+-----------
alex | 12
-----+-----------
jhon | 25
-----+-----------
alex | 12
-----+-----------
max  | 0
-----+-----------

Answer 1

I'd use a group by clause to get all the IDs, like so:

select
  Name,
  yourRandomId()
from YourTable
group by Name
having count(1) > 1

You can then use this select in a simple update command, that sets the ID for every row in this result set.

A more complete example might look something like this:

with ids as
(
    select
      Name,
      yourRandomId() as [NewId]
    from YourTable
    group by Name
    having count(1) > 1
)
update T
set [Id] = ids.[NewId]
from YourTable T
inner join ids on T.[Name] = ids.[Name];