Copying Records For Testing

I am working on a sql server SP to delete records based on inactive customer ID.

There is a table A which contains the cust-ID and the status(e.g A-active,i-inactive). My SP is fetching all the inactive cust-id records from table A and deleting the entries from other tables(around 20 tables) based on the cust-id.

I am trying to do the data set-up to test this SP but have some queries:

My approach is to copy all the impacted tables(big size) into another database for testing and tried implementing the below logic :

1)select all(inactive customers) records from table A and store it in a temp table
2) use the below sql query to copy the records

insert into DB2.<tablename>
where cust-id in (select * from temp table)

I am getting error while creating the temporary table (SQL version 2008).

1)create temporary table <tablename> - invalid keyword temporary
2) create table #<tablename> - the table is getting created but is not getting deleted thereby if I run it the next time it says table already exists. This doesn't seems to be the property of temp table.

Both the above syntax are not working.

Also, will temporary table be a good way (performance wise) or can I use the below sysntax for all the 20 impacted tables :

insert into DB2.<tablename>
where cust-id in (select cust-id from table A where cust-status = 'I')

will it degrade the performance . The records to be copied for testing is around few hundreds for each table.