How to fix the request so that only unique field values ​​get into the output?

Question

SQL

Hello. There is a request: How to remake it so that the b field in the output is unique, i.e. repeated 1 time? The values ​​of the remaining fields can be any valid (taken from this table).

SELECT a, b, c, d FROM my_table;

Answer 1

Select b, min(a) a, min(c) c 
From table
Group by b;