How to use Group by to find out the smallest value in the specified sort group

The table structure is as follows:
--------------------------------------------------
A1 A2
USA 99
USA 94
USA 95
United States 88
United States 70
United States 94
United Kingdom 79
United Kingdom 92
.........

Query results should be grouped in the order specified in A1, e.g. (USA, China, UK)
The A2 of the smallest value in the group

The results are as follows----------------------
A1 A2
United States 70
USA 94
United Kingdom 79

Reply to discussion (solution)

SELECT A1,min (A2) as A2 from Test GROUP by A1 ORDER by Find_in_set (A1, ' United States, China, United Kingdom ');

