Question

I understand that this question refers to the trivial

so I have two tables(one to many):

1) rules – id, description

2) result – id, rule_id, result of the rule, date

I want get last result fo each rule from second table

Answer 1

SELECT ru.id, ru.description, re.result_of_the_rule, re.date
    FROM (SELECT rule_id, MAX(date) AS MaxDate
              FROM result
              GROUP BY rule_id) q
        INNER JOIN rules ru
            ON q.rule_id = ru.id
        INNER JOIN result re
            ON q.rule_id = re.rule_id
                AND q.MaxDate = re.date