Question: We have already created the database framework, with all the relations and dependencies. But inside the tables were just the dummy data, and we need to get rid of these dummy data, and start adding the correct ones. How can we clear everything and leave the primary keys (IsIdentity: yes) back to zero, and also without affecting the foreign-table relational structure.

Thanks a lot!

Answer: 
I'd use TRUNCATE:

```
-- Truncate table (very fast, and it resets Identity as well)
EXEC sp_MSForEachTable "TRUNCATE TABLE ?"

```

Of course, disable and re-enable check constraints too, as suggested by kristof.
Reseeding:

DBCC CHECKIDENT (yourtable, reseed, 1)

is for setting the primary key on 1

delete from table should delete the data, but not affect any other things.