query containing entries that begin with same 3 letters as at least one other entry?

Dialect: MS SQL
How do i create a table from another table containing only those beginning with the same three letters as another entry in the table
so...
abc hello
abc goodbye
ghj must
ghjsomthing

would all be in the new table

Dialect: MS SQL

SQL:

insert into dups select * from scores where substring(player from 1 for 3) in (select substring(player from 1 for 3) from scores group by substring(player from 1 for 3) having count(*) > 1);

Please, do not hesitate to ask for clarifications if so is needed.
I would be glad to hear back from you whether the above worked or not.

Best Regards,

Dimitar

Dialect: MS SQL
Not really an answer, but perhaps a hint: check the manual for whether the is supported by MS SQL. If so it would replace the rightmost select with the group by and having clause, like this

SQL:

... unique (select substring(player from 1 for 3) from scores)

.
Hopefully it will be faster.