SQL find duplicates and assign group number

Question

The situation
On Microsoft SQL Server 2008, I have about 2 million rows. (this never happened, but we inherited the situation). Sample as follows:

usernum. |  phone  |  email
1        |  123    |  [e-mail]
2        |  123    |  [e-mail]
3        |  245    |  [e-mail]
4        |  678    |  [e-mail]

Goal
I would like to create a table that looks like this. The idea is that if the “phone” or “email” are the same, they are assigned the same group number.

groupnum |usernum. |  phone  |  email
1        |  1      |  123    |  [e-mail]
1        |  2      |  123    |  [e-mail]
2        |  3      |  245    |  [e-mail]
2        |  4      |  678    |  [e-mail]

python script, :
- usernum
-
- ,

- , usernum ( - )


Python script , . , , 10 000 , 2 . , t-sql, , python script, pyodbc.
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Answer 1

, , . , , , . , , ( ), ( ):

insert into yourGroupsTable (phone, email) -- assuming identity column of groupNum here
select distinct phone, email
from yourUserTable

-- assign group nums with priority on matching phone AND email
update yourUserTable
set groupNum = g.groupNum
from yourUserTable u
join yourGroupsTable g on u.phone = g.phone
    and u.email = g.email

, , GroupsTable - . , , ( ) - :

:

groupnum |usernum. |  phone  |  email
1        |  1      |  123    |  [e-mail]
1        |  2      |  123    |  [e-mail]
?        |  3      |  245    |  [e-mail]
?        |  4      |  678    |  [e-mail]
?        |  5      |  245    |  [e-mail]
?        |  6      |  678    |  [e-mail]  

?

Answer 2

python script, ... mysql, ,

  THEN groupnum groupnum ...    groupnum

,

,

5 | 678 | [e-mail]

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, [ ] , groupnum.

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