Can this query be improved/optimized ? Join query with 2 tables
I got 2 tables like such:
Record
table:
code | date |
---|---|
0001 | 2020-12-31 |
0001 | 2020-12-30 |
0002 | 2021-01-04 |
0002 | 2020-12-31 |
Valid_date
table, the dates here ain’t linear:
date |
---|
2021-01-06 |
2021-01-05 |
2021-01-04 |
2020-12-31 |
2020-12-30 |
2020-12-29 |
The result I want is the next valid date of each code:
code | next_date |
---|---|
0001 | 2021-01-04 |
0002 | 2021-01-05 |
My current take is like this, using sub query. I got the result that I need but it seems not the best way. Any hints for better syntax ?
SELECT sub.code,
Min(sub.date)
FROM (SELECT jt.code,
rc.date
FROM record rc,
(SELECT code,
Max(date) mdate
FROM record
GROUP BY code) AS jt
WHERE rc.date > jt.mdate
ORDER BY jt.code) AS sub
GROUP BY sub.code