How to calculate the average per day for different years - sql

Question

I am trying to calculate the average number of times apple with an increment of 3 are shown per day in the years of both 2018 and 2017. To do this I am trying to use setNum and exNum that has a difference of 3.
ID Year Text setNum ExNum
-------------------------------------------------
1 2018-01-21 apple 1 3
2 2017-08-03 apple 2 5
3 2018-03-02 banana 1 3
4 2018-05-22 apple 1 3
5 2018-12-12 apple 3 6
6 2017-04-13 apple 3 6
My current query to obtain this is:
SELECT
2017 = avg(case when Year BETWEEN '2017-01-01' AND '2017-12-31' then 1 else 0 end),
2018 = avg(case when Year BETWEEN '2018-01-01' AND '2018-12-31' then 1 else 0 end)
FROM
exampleTable
WHERE
Text LIKE '%apple%'
This currently outputs:
2017 2018
0 0
Note: The original table had a single text column Increment, which had values like 1-3. That is, the 1-3 represented a setNum of 1 and an ExNum of 3.

Answer 1

Your decision to store a numerical increment range as text is not a good one, and ideally you should be storing the two points of the increment in separate columns. That being said, we can do some string olympics to work around this:
SELECT
YEAR(Year) AS Year,
COUNT(CASE WHEN 3 BETWEEN CAST(LEFT(Increment, CHARINDEX('-', Increment)-1) AS int) AND
CAST(RIGHT(Increment, LEN(Increment) - CHARINDEX('-', Increment)) AS int)
THEN 1 END) AS apple_3_cnt
FROM exampleTable
WHERE
TEXT LIKE '%apple%'
GROUP BY
YEAR(year);
Demo
Here I am aggregating by year, and then taking a conditional count of record, for each year, where the apple increment range contains 3. To do this, I separate out the two ends of the increment range, and then convert them to integers.
Edit:
Based on your updated table, we can try a simpler query:
SELECT
YEAR(Year) AS Year,
COUNT(CASE WHEN 3 BETWEEN setNum AND ExNum THEN 1 END) AS apple_3_cnt
FROM exampleTable
WHERE
TEXT LIKE '%apple%'
GROUP BY
YEAR(year);

Answer 2

Try below
SELECT
avg(case when Year BETWEEN '2017-01-01' AND '2017-12-31' then setNum+ExNum end) as 2017
avg(case when Year BETWEEN '2018-01-01' AND '2018-12-31' then setNum+ExNum end) as 2018
FROM
exampleTable
WHERE
Text LIKE '%apple%'

Answer 3

Your query is fine. The only problem is how and to where you assign the results.
Use this syntax instead
SELECT
avg(case when Year BETWEEN '2017-01-01' AND '2017-12-31' then 1 else 0 end) as A2017,
avg(case when Year BETWEEN '2018-01-01' AND '2018-12-31' then 1 else 0 end) as A2018
FROM
exampleTable
WHERE
Text LIKE '%apple%'
Note that you can't use numbers as variable names.