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I have two tables in SQL and I need to be able to do a join based off of the timestamp in table B that is earlier than or equal to the timestamp in table A.
So, here is some fake data for two tables and the desired output:
Closed Cases (Table A)
| id | resolution | timestamp | ------------------------------------------------ | 1 | solved | 2006-10-05 11:55:44.888153 | | 2 | closed | 2007-10-07 12:34:17.033498 | | 3 | trashed | 2008-10-09 08:19:36.983747 | | 4 | solved | 2010-10-13 04:28:14.348753 |
Classification (Table B)
| id | value | timestamp | ------------------------------------------------- | 1 | freshman | 2006-01-01 12:02:44.888153 | | 2 | sophomore | 2007-01-01 12:01:19.984333 | | 3 | junior | 2008-01-01 12:02:28.746149 |
Desired Results
| id | resolution | timestamp | value | -------------------------------------------------------------- | 1 | solved | 2006-10-05 11:55:44.888153 | freshman | | 2 | closed | 2007-10-07 12:34:17.033498 | sophomore | | 3 | trashed | 2008-10-09 08:19:36.983747 | junior | | 4 | solved | 2010-10-13 04:28:14.348753 | junior |
So, I know the code needs to look like the following, I just can't figure out what to do with the ON portion of the JOIN ($1 and $2 are variables that will be passed in):
SELECT case.id, case.resolution, case.timestamp, class.value
FROM closed_cases AS case
LEFT JOIN classifications AS class ON ???
WHERE case.timestamp BETWEEN $1 AND $2;
I know I could use a sub-select, but this will be operating on at least a few thousand rows, probably more, and I need it to be really fast; so I was hoping for a simple clause that could do it.