[SOLVED] How to change db connection in CI

i want to dump my old db to my new db design which have different stucture.
i dump all my table and save query using get_compiled_insert() to file.

the problem is my old db is sql server and my new db is mysql

example
$this->db->set(['id'=>1, 'name'=>'john'])->get_compiled_insert('table');

result : INSERT INTO "table" ("id", "name") VALUES ('1', 'john')


this is valid sql server query but not in mysql, because the right query in mysql is: INSERT INTO `table` (`id`, `name`) VALUES ('1', 'john')

conclusion:
script: $this->db->set(['id'=>1, 'name'=>'john'])->get_compiled_insert('table');
with sql server connection: INSERT INTO "table" ("id", "name") VALUES ('1', 'john')
with mysql connection: INSERT INTO `table` (`id`, `name`) VALUES ('1', 'john')

what i want is dump sql server data to build mysql query. 
i really can solve this with my own code (build query manually), but i want to do the right way in CI.

How to do this in the right way(best practice)?
maybe i can dump the data using sql server connection and build compiled query using mysql connection.
thanks