I have a table that looks something like this:
| id | fk1 | fk2 | version |
| 1 | 1 | 1 | 1 |
| 2 | 1 | 1 | 2 |
| 3 | 1 | 1 | 3 |
Having on hand the values of fk1 and fk2 I am trying to get the record with the highest value for version. Currently what I am doing is this:
version = Project.where("fk1= ? AND fk2= ?", params.require(:fk1), params.require(:fk2)).maximum(:version)
@project = Project.find_by_fk1_and_fk2_and_version(params.require(:fk1), params.require(:fk2), version)
This gets me the correct record, but I have to execute 2 queries for something that seems really simple in theory, but after trying a number of different things I had no luck with doing this with a single query. I am envisioning something like:
version = Project.where("fk1= ? AND fk2= ? AND max(version)", params.require(:fk1), params.require(:fk2))
or something.
Well the rails way to do that is
Project.where(fk1: params.require(:fk1), fk2: params.require(:fk2)).
order('version desc').first
Which translates to an sql query like:
SELECT * FROM projects WHERE fk1 = "fk1" AND fk2 = "fk2" ORDER BY version DESC LIMIT 1;
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