how to set up query to pull Magento customer information

I had most of this query worked out, or so I thought, except for two things, large things, one, as soon as I add the forth table [departments_tbl]into the query, I get about 800 rows returned when I should only have about 100.

See the attached schema, note the checkmarks, these are the fields I want returned.
In a nutshell I want email, first/last name, billing_state, store_name, lastlogin, customer_grp_code, manager and manager_email [I have checked a few other in the image, but these are the main ones].  Also please note that entity_id and cust_id fields would the be links between the _ncust_rpt_copy table and the _n_cust_entity_storeid_15 tbl

This won't help, but here is just one of the queries that I almost had working, until the [department_tbl was added to the mix]

SELECT _n_cust_entity_storeid_15.entity_id, 
    _n_cust_entity_storeid_15.email, 
    customer_group.customer_group_code, 
    departments.`name`, 
    departments.manager, 
    _n_cust_rpt_copy.first_name, 
    _n_cust_rpt_copy.last_name, 
    _n_cust_rpt_copy.last_login_date, 
    _n_cust_rpt_copy.billing_address, 
    _n_cust_rpt_copy.billing_city, 
    _n_cust_rpt_copy.billing_state, 
    _n_cust_rpt_copy.billing_zip
FROM _n_cust_entity_storeid_15 INNER JOIN customer_group ON _n_cust_entity_storeid_15.group_id = customer_group.customer_group_id
     INNER JOIN departments ON _n_cust_entity_storeid_15.store_id = departments.store_id, 
    _n_cust_rpt_copy
ORDER BY _n_cust_rpt_copy.last_name ASC

Select allOpen in new window

I've tried subqueries, joins, but just can't get it to work.

Any help would be greatly appreciated.