Once Sales Order get booked, There will be record go into mtl_sales_orders.
Unlike account numbers which are stored as flexfields in GL_CODE_COMBINATIONS, or purchase orders which are stored in PO_HEADERS, sales orders are not assumed to originate in any particular application.
Query to connect Order Sales Order Header and MTL Sales Order Table
SELECT S.SALES_ORDER_ID,S.SEGMENT1, S.SEGMENT2,S.SEGMENT3,H.ORDER_NUMBER,H.FLOW_STATUS_CODE,H.SOLD_TO_ORG_ID,H.OPEN_FLAG
FROM MTL_SALES_ORDERS S,OE_ORDER_HEADERS_ALL H
WHERE S.SEGMENT1 = TO_CHAR(H.ORDER_NUMBER)
AND H.ORDER_NUMBER = '12345';