What are the code and description of the least frequent detention type ?
create table ref_detention_type (detention_type_description varchar, detention_type_code varchar, PRIMARY KEY (detention_type_description)); create table detention (detention_type_code varchar, PRIMARY KEY (detention_type_code))
select t1.detention_type_code, t2.detention_type_description from detention as t1 join ref_detention_type as t2 on t1.detention_type_code = t2.detention_type_code group by t1.detention_type_code order by count(*) limit 1