This command should be put in the edit query section of the Microsoft Query:

 

Select  cast(  left(customer_since_date,4)  +'-'+ right(left(customer_since_date,6),2)  +'-'+ right(customer_since_date,2)  as date)  ,  cast (customer_since_date as integer) , customer.customer_id, customer.customer_name, customer.lookup_description, customer.main_address_1, customer.main_address_2, customer.main_city, customer.main_state, customer.main_country, customer.main_zip_code, customer.main_phone_area_code, customer.main_phone, customer.main_fax_area_code, customer.main_fax, customer.bill_address_name, customer.bill_address_1, customer.bill_address_2, customer.bill_city, customer.bill_state, customer.bill_country, customer.bill_zip_code, customer.bill_phone_area_code, customer.bill_phone, customer.bill_phone_ext, customer.bill_fax_area_code, customer.bill_fax, customer.bill_contact_no, customer.pm_address_name, customer.pm_address_1, customer.pm_address_2, customer.pm_city, customer.pm_state, customer.pm_country, customer.pm_zip_code, customer.pm_set_to_physical, customer.pp_address_name, customer.pp_address_1, customer.pp_address_2, customer.pp_city, customer.pp_state, customer.pp_country, customer.pp_zip_code, customer.pp_phone_area_code, customer.pp_phone, customer.pp_phone_ext, customer.pp_fax_area_code, customer.pp_fax, customer.pp_contact_no, customer.ship_address_name, customer.ship_address_1, customer.ship_address_2, customer.ship_city, customer.ship_state, customer.ship_country, customer.ship_zip_code, customer.ship_phone_area_code, customer.ship_phone, customer.ship_phone_ext, customer.ship_fax_area_code, customer.ship_fax, customer.ship_will_call, customer.ship_contact_no, customer.route_id, customer.territory, customer.customer_comments, customer.tax_id, customer.po_required, customer.customer_type, customer.outside_salesagent_1, customer.outside_salesagent_2, customer.number_of_chg_sales, customer.number_of_days_paid, customer.last_sale_date, customer.ytd_sales, customer.ytd_cogs, customer.ytd_no_of_sales, customer.ytd_sales_last_yr, customer.ytd_cogs_last_yr, customer.ytd_no_sales_last_yr, customer.high_credit_balance, customer.customer_since_date, customer.allow_credit_terms, customer.credit_limit, customer.credit_terms_code, customer.customer_credit_hold, customer.default_payment_type, customer.pricing_method, customer.pricing_column, customer.starting_price_level, customer.default_markup_rate, customer.min_profit_margin, customer.price_adder_row, customer.price_adder_column, customer.max_skid_weight, customer.sales_tax_code_1, customer.sales_tax_code_2, customer.sales_tax_code_3, customer.sales_tax_code_4, customer.sales_tax_code_5, customer.branch_id, customer.print_statements, customer.sic_code, customer.default_currency, customer.default_po_no, customer.quick_quote_note_1, customer.quick_quote_note_2, customer.inactive, customer.ship_note_id, customer.resale_exp_date, customer.outside_salesagent_3, customer.outside_salesagent_4, customer.outside_salesagent_5, customer.default_warehouse, customer.fin_chg_assess_date, customer.default_so_no, customer.fed_tax_id, customer.invoice_via, customer.default_ship_via, customer.attached_file, customer.intercompany  FROM customer customer