Overlapping periods

[Anonymous]

Dear colleagues!

I've got some problems with connecting data:
1. Managers and sales. Example:

Manager_history:

Manager	Object	Manager_date_appointment
Alex	123	26.10.2017
Nick	123	03.07.2018
Jack	124	01.08.2018
Ivan	125	15.10.2017
Alex	125	01.03.2018
Jack	125	13.07.2018

Sales:

Object	Sales_date	Sales
123	27.10.2017	100
123	30.11.2017	150
123	05.08.2018	300
123	06.08.2018	200
124	01.09.2018	500
124	13.10.2018	340
125	17.10.2017	170
125	19.10.2017	300
125	02.04.2018	650
125	03.05.2018	322
125	11.08.2018	432
125	10.10.2018	600

How can i get sales in the context of managers? (needed result below)

Manager	Sum_sales
Alex	100+150+650+322=1222
Nick	300+200=500
Jack	500+340+432+600=1872
Ivan	170+300=470

2. Building stage and sales. The same data + stages of objects with interval dates such as:

Object	Building_stage	Stage_start	Stage_end
123	Foundation	01.01.2016	04.08.2018
123	Roof	05.08.2018	01.10.2019
124	Construction of floors	01.01.2017	20.10.2018
125	Foundation	01.05.2016	13.12.2017
125	Construction of floors	14.12.2017	01.05.2018
125	Roof	02.05.2018	11.11.2019

The idea of needed results is the same (sales in the context of building stages):

Building_stage	Sum_sales
Foundation	100+150+170+300=720
Construction of floors	500+340+650=1490
Roof	300+200+322+432+600=1854

I'll be grateful for all advice. Thanks a lot.