How do I count data from 2 different tables by date - sql

Question

I have 2 tables with no relations, both tables have different number of columns, but there are a few columns that are the same but hold different data. I was able to create a function or view of only the data I wanted, but when I try to count the data by filtering the date, I always get the wrong count in return. Let me explain by showing the 2 functions and what I try to do:
Function 1
ID - number from 1 to 8
data sent - YES or NO
Date - date value
Function 2
ID - number from 1 to 8
data sent - yes or no
date - date value
Upon running both separately, I get all the rows from the tables and everything looks good.
Then I try to add the following to each function:
select
count([data sent]), ID
from function1
Where (date between #date1 and #date2)
group by ID
The above statement works great and gives me the right result for each function.
Now I thought what if I want to add those 2 functions into one and get the count from both functions on 1 page.
So I created the following function:
Function 3
select
count(Function1.[data sent]) as Expr1,
Function1.id,
count(Function2.[data sent]) as Expr2,
Function1.date
from
Function1
LEFT OUTER JOIN
Function2 on Function1.id = Function2.id
Where
(Function1.date between #date1 and #date2)
group by
Function1.id
Upon running the above, I get the following table:
ID Expr1 Expr2
On both Expr1 and Expr2, I get results which I am not sure where they come from. I guess something is being multiplied by 100000 since one table holds almost 15000 rows and the other around 5000 rows.
What I would like to know first is if it possible at all to be able to filter by date and count records from both table at the same time. If anyone need more information please let me know and I will be glad to share and explain more.
Thank you

Answer 1

The LEFT OUTER JOIN is taking each row of the left table, finding ALL of the rows in the right table with the same id field, and creating that many rows in the result table. Since id isn't what we usually think of as an identity field (it looks more like a "deviceId" or something), you'll get lots of matches for each one. Repeat 15000 times and you get your combinatorial explosion.
Tip: To debug things like this, you can create sample tables with a tiny subset of the real data, say 10 rows from each, and run your query on them. You'll see the issue immediately.
It's possible to filter by date. It's hard to recommend an actual solution without better understanding your phrase "I want to add those 2 functions into one and get the count from both functions on 1 page".

Answer 2

Why can't you create a temporary table for each function then join them together?

Answer 3

Maybe subqueries can help you to achieve what you want:
SELECT
ID = COALESCE(f1.ID, f2.ID),
Date = COALESCE(f1.Date, f2.Date),
f1.Expr1,
f2.Expr2
FROM (
SELECT
ID,
Date,
Expr1 = COUNT([data sent])
FROM Function1
WHERE Date BETWEEN #date1 AND #date2
GROUP BY
ID,
Date
) f1
FULL JOIN (
SELECT
ID,
Date,
Expr2 = COUNT([data sent])
FROM Function2
WHERE Date BETWEEN #date1 AND #date2
GROUP BY
ID,
Date
) f2
ON f1.ID = f2.ID AND f1.Date = f2.Date
This query also uses full (outer) join instead of left join, in case the right side of the join contains rows that have no match in the left side (and you want those rows).