시간 순으로 최신 데이터 뽑는 유형

SELECT * FROM (
    SELECT *, ROW_NUMBER() OVER (PARTITION BY tag_no ORDER BY time DESC) as rn
    FROM your_table
) t
WHERE t.rn = 1;

SELECT DISTINCT ON (tag_no) *
FROM your_table
ORDER BY tag_no, time DESC;

SELECT t.*
FROM your_table t
INNER JOIN (
    SELECT tag_no, MAX(time) as max_time
    FROM your_table
    GROUP BY tag_no
) tm ON t.tag_no = tm.tag_no AND t.time = tm.max_time;

SELECT * FROM your_table_name ORDER BY some_column DESC LIMIT 1;