Can someone help me with this join - sql

Question

I need it to give me me a total of 0 for week 33 - 39, but I'm really bad with joining 3 tables and I cant figure it out
Right now it only gives me an answer for dates that there are actual records in the tracker_weld_table.
SELECT SUM(tracker_parts_archive.weight),
WEEK(mycal.dt) as week
FROM
tracker_parts_archive, tracker_weld_archive
RIGHT JOIN
(SELECT dt FROM calendar_table WHERE dt >= '2018-7-1' AND dt <= '2018-10-1') as mycal
ON
weld_worker = '133'AND date(weld_dateandtime) = mycal.dt
WHERE
tracker_weld_archive.tracker_partsID = tracker_parts_archive.id
GROUP BY week

Answer 1

I think you are trying for something like this:
SELECT WEEK(c.dt) as week, COALESCE(SUM(tpa.weight), 0)
FROM calendar_table c left join
tracker_weld_archive tw
on date(tw.weld_dateandtime) = c.dt left join
tracker_parts_archive tp
on tw.tracker_partsID = tp.id and tp.weld_worker = 133
WHERE c.dt >= '2018-07-01' AND c.dt <= '2018-10-01'
GROUP BY week
ORDER BY week;
Notes:
You want to keep all (matching) rows in the calendar table, so it should be first.
All subsequent joins should be LEFT JOINs.
Never use commas in the FROM clause. Always use proper, explicit, standard JOIN syntax.
Write out the full proper date constant -- YYYY-MM-DD. This is an ISO-standard format.
I am guessing that weld_worker is a number, so single quotes are not needed for the comparison.

Answer 2

First, lets start with understanding what you want.. You want totals per week. This means there will be a "GROUP BY" clause (also for any MIN(), MAX(), AVG(), SUM(), COUNT(), etc. aggregates). What is the group BY basis. In this scenario, you want per week. Leading to the next part that you want for a specific date range qualified per your calendar table.
I would start in order what WHAT filtering criteria first. Also, ALWAYS TRY to identify all table( or alias).column in your queries so anyone after you knows where the columns are coming from, especially when multiple tables. In this case "ct" is the ALIAS for "Calendar_Table"
SELECT
ct.dt
from
calendar_table ct
where
ct.dt >= '2018-07-01'
AND ct.dt <= '2018-10-01'
Now, the above date looks to be INCLUSIVE of October 1 and looks like you are trying to generate a quarterly sum from July, Aug, Sept. I would change to LESS than Oct 1.
Now, your calendar has many days and you want it grouped by week, so the WEEK() function gets you that distinct reference without explicitly checking every date. Also, try NOT to use reserved keywords as final column names... makes for confusion later on sometimes.
I have aliased the column name as "WeekBasis". Here, I did a COUNT(*) just to show the total days and the group by showing it in context.
SELECT
WEEK( ct.dt ) WeekBasis,
MIN( ct.dt ) as FirstDayOfThisWeek,
MAX( ct.dt ) as LastDayOfThisWeek,
COUNT(*) as DaysInThisWeek
from
calendar_table ct
where
ct.dt >= '2018-07-01'
AND ct.dt <= '2018-10-01'
group by
WEEK( ct.dt )
So, at this point, we have 1 record per week within the date period you are concerned,
but I also grabbed the earliest and latest dates just to show other components too.
Now, lets get back to your extra tables. We know the dates in question, now need to
get the details from the other tables (which is lacking in the post. You should post
critical components such as how tables are related via common / joined column basis.
How is tracker_part_archive related to tracker_weld_archive??
To simplify your query, you dont even NEED your calendar table as the welding
table HAS a date field and you know your range. Just query against that directly.
IF your worker's ID is numeric, don't add quotes around it, just leave as a number.
SELECT
WEEK( twa.Weld_DateAndTime ) WeekBasis,
COUNT(*) WeldingEntriesDone,
SUM(tpa.weight) TotalWeight
from
tracker_weld_archive twa
JOIN tracker_parts_archive tpa
-- GUESSING on therelationship here.
-- may also be on a given date too???
-- all pieces welded by a person on a given date
ON twa.weld_worker = tpa.weld_worker
AND twa.Weld_DateAndTime = tpa.Weld_DateAndTime
where
twa.Weld_Worker = 133
AND twa.Weld_DateAndTime >= '2018-07-01'
AND twa.Weld_DateAndTime <= '2018-10-01'
group by
WEEK( twa.Weld_DateAndTime )
IF you provide the table structures AND sample data, this can be refined a bit more for you.