MySQL Select DISTINCT multiple columns based on the uniqueness of one row?

Question

I\'m trying to understand what this query does exactly:

SELECT DISTINCT `state`, `state_name` FROM `geo` ORDER BY `state_name` ASC

All I\'m

Answer 1

DISTINCT will return only distinct rows, so:

Is my query checking both columns for uniqueness or just state?

Both columns

You could also switch to GROUP BY instead.

SELECT `state`, `state_name` FROM `geo` group by 'state', 'state_name' ORDER BY `state_name` ASC 

Answer 2

It's checking for unique combinations of state and state_name. Distinct operates on all columns included in your select list.

To only include unique state values, just select distinct state