A complex SQL query

I hope someone can give me some pointers.

Here is my table.

+--------+----------+------------+-----------+

| usr_id | employer | start_date | end_date |

+--------+----------+------------+-----------+

| A | Goo | 201904 | - |

| A | Micro | 201704 | 201903 |

| B | Micro | 201706 | - |

| B | Goo | 201012 | 201705 |

| B | Micro | 201001 | 201011 |

+--------+----------+------------+-----------+

I am trying to list up people working for a company called "Micro".

Some people work for a company multiple times, like user B.

I only need one line per user, displaying only the latest affiliation date.

For user_id "B", I could do Select user_id, MAX(start_date), end_date where employer = 'Micro',

but that would fail to get record for user_id "A".

If multiple records exist, I want to do MAX, but if only a single record exists, I don't need MAX.

How do I do that?

From the above data, I would like to see only two lines:

| A | Micro | 201704 | 201903 |

| B | Micro | 201706 | - |

Thank you.

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