SQL Matching many-to-many dates for ID field - sql

Question

Edit: Fixed Start Date for User 2
I have a list of user ids, each having many start dates and many end dates.
A start date can be recorded many times after the "actual" start date of an "event", same goes for the end date.
The result should be each the first start date and first end date for each user "event"
I hope that makes sense, see the example below.
Thanks!
Assuming the Following tables are given:
Start Table:
+--------+-------------+
| UserID | Start |
+--------+-------------+
| 1 | 2019-01-01 |
| 1 | 2019-01-02 |
| 1 | 2019-01-03 |
| 1 | 2019-04-01 |
| 1 | 2019-04-02 |
| 1 | 2019-04-03 |
| 2 | 2019-06-01 |
| 2 | 2019-06-02 |
| 2 | 2019-10-01 |
| 2 | 2019-10-02 |
+--------+-------------+
End Table:
+--------+------------+
| UserID | End |
+--------+------------+
| 1 | 2019-03-01 |
| 1 | 2019-03-02 |
| 1 | 2019-03-03 |
| 1 | 2019-05-01 |
| 1 | 2019-05-02 |
| 1 | 2019-05-03 |
| 2 | 2019-08-01 |
| 2 | 2019-08-02 |
| 2 | 2019-12-01 |
| 2 | 2019-12-02 |
+--------+------------+
Result:
+--------+------------+------------+
| UserID | Start | End |
+--------+------------+------------+
| 1 | 2019-01-01 | 2019-03-01 |
| 1 | 2019-04-01 | 2019-05-01 |
| 2 | 2019-06-01 | 2019-08-01 |
| 2 | 2019-10-01 | 2019-12-01 |
+--------+------------+------------+

Answer 1

Not sure I agree with your 2019-10-02
Here is one solution
Example
Select UserID
,[Start] = min([Start])
,[End]
From (
Select A.*
,[End] = (Select min([End]) From EndTable Where UserID=A.UserID and [End] >= A.Start )
From StartTable A
) A
Group By UserID,[End]
Returns
UserID Start End
1 2019-01-01 2019-03-01
1 2019-04-01 2019-05-01
2 2019-06-01 2019-08-01
2 2019-10-01 2019-12-01