Subquery or Join

select table1.name,table2.score from table2 join table1 on table1.username = table2.username

This is equivalent and give you better picture

select t1.name as 'name', t2.score as 'score' from table2 t2
join table1 t1 on t1.username= t2.username

Run the query only show 2 columns : 'name' and 'score'

Regards