Make the correct INNER JOIN when using a BETWEEN - sql

Question

I'm sorry if this is a dumb question, but I have this particular case I can't figure how to handle. I need a query where I get all date values between two date values on another tables, and right now this is my query
SELECT h.hour_gkey, h.hour_time
FROM Hours as h
INNER JOIN ServiceHours sh ON h.hour_gkey BETWEEN sh.openhour_hour_gkey AND sh.closehour_hour_gkey;
So to explain it a bit further, the ServiceHours table has two fields openhour_hour_gkey and closehour_hourg_key that are integer, this two fields contain Foreign Keys of the Hours table and therefore they have time values, the hour_gkey(integer) its the primary key of Hours table and I need to show only the values of hour_time (date fieldtype) that are between the dates that correspond to those two fields. How could I do that
Using right now SQL Server 2014

Answer 1

I'm interpreting your question to be "How do I select all of the rows of Hours whose hour_time values are between those related to ServiceHours.openhour_hour_gkey and ServiceHours.closehour_hour_gkey?"
I furthermore suppose that it is intentional that you are neither selecting any columns from ServiceHours nor filtering to narrow the results to those associated with a single ServiceHours row. Thus, if there are multiple ServiceHour rows you will get a set of Hours rows for each one, with these sets not necessarily being disjoint, and with no indication of which goes with which ServiceHour.
In any case, you need to perform a join for each relationship you want to traverse, and for this query you seem to want another join to get the target data. that might look like this:
SELECT h.hour_gkey, h.hour_time
FROM
Hours h
CROSS JOIN ServiceHours sh
INNER JOIN Hours sho
ON sh.openhour_hour_gkey = sho.hour_gkey
INNER JOIN Hours shc
ON sh.closehour_hour_gkey = shc.hour_gkey
WHERE h.hour_time BETWEEN sho.hour_time AND shc.hour_time;
I have written the BETWEEN condition as a filter predicate instead of a join predicate because that seems a better characterization. For inner joins, however, the two alternatives are equivalent. Note also that this query is semantically equivalent to #DaveCosta's.

Answer 2

Here is one way I think it could be done. I am not certain if the syntax is exactly right for SQL Server. But the basic idea is, you would need to join from ServiceHours to Hours to get the actual open/close hour values, then select the rows from Hours with values in that range.
WITH min_max AS (
SELECT h1.hour_time min_hour_time, h2.hour_time max_hour_time
FROM ServiceHours sh
JOIN Hours h1 ON h1.hour_gkey = sh.openhour_hour_gkey
JOIN Hours h2 ON h2.hour_gkey = sh.closehour_hour_gkey
)
SELECT h.hour_time
FROM Hours h
JOIN min_max ON h.hour_time BETWEEN min_max.min_hour_time AND min_max.max_hour_time
(Note I'm assuming that ServiceHours has only one row. If it doesn't, there is probably some other field you want to include in both the subquery and the main query to indicate which row in ServiceHours each resulting row relates to.)