MySQL SELECT DISTINCT multiple columns

Question

Let's say I have columns a, b c, d in a table in a MySQL database. What I'm trying to do is to select the distinct values of ALL of these 4 columns in my table (only the distinct values). I tried stuff like:

SELECT DISTINCT a,b,c,d FROM my_table; SELECT DISTINCT a,b,c,d FROM my_table GROUP BY a,b,c,d; 

None of those worked. Can anybody help out here?

Thank you

NOTE I want the distinct values of the columns a, b, c d separately. Not the distinct combination of values

Answer 1

I know that the question is too old, anyway:

SELECT a, b FROM mytable GROUP BY a, b; 

This will give your all the combinations.

Answer 2

can this help?

select  (SELECT group_concat(DISTINCT a) FROM my_table) as a, (SELECT group_concat(DISTINCT b) FROM my_table) as b, (SELECT group_concat(DISTINCT c) FROM my_table) as c, (SELECT group_concat(DISTINCT d) FROM my_table) as d