Table Join 소요시간 (MySQL)

* Table Join 소요시간 (MySQL)

inner join이 self join보다 빠름 : 테이블의 내부검색시(테이블 1개를 2개로 간주)


select a.customized_id, a.value, a.custom_field_id from
(select customized_id, value, custom_field_id  from custom_values as a where (custom_field_id = 17 and value = 'AMAT')) as a
inner join
(select customized_id, value, custom_field_id from custom_values as b where (custom_field_id = 1 and value = 'ETCH')) as b
/* 0 rows affected, 38 rows found. Duration for 1 query: 0.016 sec. */


select a.customized_id from custom_values a, custom_values b
where
    (a.custom_field_id = 17 and a.value = 'AMAT')
and (b.custom_field_id = 1 and b.value = 'ETCH')
and a.customized_id = b.customized_id
/* 0 rows affected, 38 rows found. Duration for 1 query: 0.124 sec. */