Calculating averages in SQL Server without ignoring null values - sql

Question

I have a query like below:
DECLARE #t TABLE
(
EmpName VARCHAR(10)
, Qty INT
, Item VARCHAR(12)
)
INSERT INTO #t
VALUES ('Jane',3,'Dog')
, ('Carle',1,'Cat')
, ('Abay',5,'Goat')
, ('Jane',1,'Dog')
, ('Carle',10,'Cat')
, ('Jane',2,'Dog')
, ('Jane',8,'Goat')
, ('Jane',3,'Ram')
, ('Carle',2,'Dog')
--SELECT * FROM #t
SELECT
EmpName, [Dog], [Cat], [Goat], [Ram]
FROM
(SELECT
EmpName, Qty, Item
FROM #t) AS b
PIVOT(SUM(Qty) FOR Item IN ([Dog], [Cat], [Goat], [Ram])) AS p
And the result is as seen in the screenshot below:
I want to calculate the average Qty across Item without ignoring null values in the calculation. For example, in row 1, EmpName Abay should be 5 divided by 4 (number of columns), as seen in this screenshot:
How do I get the average column?

Answer 1

I'm not really familiar with the PIVOT query, so here is an alternative using conditional aggregation:
SELECT
Empname,
Dog = SUM(CASE WHEN Item = 'Dog' THEN Qty ELSE 0 END),
Cat = SUM(CASE WHEN Item = 'Cat' THEN Qty ELSE 0 END),
Goat = SUM(CASE WHEN Item = 'Goat' THEN Qty ELSE 0 END),
Ram = SUM(CASE WHEN Item = 'Ram' THEN Qty ELSE 0 END),
Average = SUM(ISNULL(Qty, 0))/ 4.0
FROM #t
GROUP BY EmpName;
Note that this will only work if you only have 4 Items. Otherwise, you need to resort to dynamic crosstab.
ONLINE DEMO
For dynamic crosstab, I used a temporary table instead of a table variable:
DECLARE #sql NVARCHAR(MAX) = '';
SELECT #sql =
'SELECT
Empname' + CHAR(10);
SELECT #sql = #sql +
' , SUM(CASE WHEN Item = ''' + Item + ''' THEN Qty ELSE 0 END) AS ' + QUOTENAME(Item) + CHAR(10)
FROM (
SELECT DISTINCT Item FROM #t
) t;
SELECT #sql = #sql +
' , SUM(ISNULL(Qty, 0)) / (SELECT COUNT(DISTINCT Item) * 1.0 FROM #t) AS [Average]' + CHAR(10) +
'FROM #t
GROUP BY EmpName;';
ONLINE DEMO

Answer 2

Try a combination of AVG and ISNULL, i.e. AVG(ISNULL(Dog, 0)).

Answer 3

One simple method is:
select empname, goat, cat, dog, ram,
(coalesce(goat, 0) + coalesce(cat, 0) + coalesce(dog, 0) + coalesce( ram, 0)
) / 4.0 as average
from t;
Another simple method uses outer apply:
select t.*, v.average
from t outer apply
(select avg(coalesce(x, 0))
from (values (t.goat), (t.cat), (t.dog), (t.ram)
) v(x)
) v(average);

Answer 4

DECLARE #t TABLE
(
EmpName VARCHAR(10)
, Qty INT
, Item VARCHAR(12)
)
INSERT INTO #t
VALUES ('Jane',3,'Dog')
, ('Carle',1,'Cat')
, ('Abay',5,'Goat')
, ('Jane',1,'Dog')
, ('Carle',10,'Cat')
, ('Jane',2,'Dog')
, ('Jane',8,'Goat')
, ('Jane',3,'Ram')
, ('Carle',2,'Dog')
SELECT EmpName
, [Dog]
, [Cat]
, [Goat]
, [Ram]
,p.total/4.0 as av
FROM (SELECT EmpName, Qty, Item,SUM(qty)OVER(PARTITION BY EmpName) AS total FROM #t) AS b
PIVOT(SUM(Qty) FOR Item IN([Dog],[Cat],[Goat],[Ram])) AS p
EmpName Dog Cat Goat Ram av
---------- ----------- ----------- ----------- ----------- ---------------------------------------
Abay NULL NULL 5 NULL 1.250000
Carle 2 11 NULL NULL 3.250000
Jane 6 NULL 8 3 4.250000
V2: Dynamic script:
CREATE TABLE #t
(
EmpName VARCHAR(10)
, Qty INT
, Item VARCHAR(12)
)
INSERT INTO #t
VALUES ('Jane',3,'Dog')
, ('Carle',1,'Cat')
, ('Abay',5,'Goat')
, ('Jane',1,'Dog')
, ('Carle',10,'Cat')
, ('Jane',2,'Dog')
, ('Jane',8,'Goat')
, ('Jane',3,'Ram')
, ('Carle',2,'Dog')
INSERT #t ( EmpName, Qty, Item )VALUES('Abay',100,'abc')
DECLARE #cols VARCHAR(max),#sql VARCHAR(MAX),#cnt INT
SELECT #cols=ISNULL(#cols+',[','[')+Item+']',#cnt=ISNULL(#cnt+1,1) FROM #t GROUP BY Item
PRINT #cols
PRINT #cnt
SET #sql='SELECT EmpName, '+#cols+',p.total*1.0/'+LTRIM(#cnt)+' as av'+CHAR(13)
+' FROM (SELECT EmpName, Qty, Item,SUM(qty)OVER(PARTITION BY EmpName) AS total FROM #t) AS b'+CHAR(13)
+' PIVOT(SUM(Qty) FOR Item IN('+#cols+')) AS p'
EXEC(#sql)
EmpName abc Cat Dog Goat Ram av
---------- ----------- ----------- ----------- ----------- ----------- ---------------------------------------
Carle NULL 11 2 NULL NULL 2.600000
Jane NULL NULL 6 8 3 3.400000
Abay 100 NULL NULL 5 NULL 21.000000

Answer 5

Avoid NULL from your pivot sentence and compute AVG.
;with ct as
(
SELECT EmpName
, ISnull([Dog],0) Dog
, ISnull([Cat],0) Cat
, ISnull([Goat],0) Goat
, ISnull([Ram],0) Ram
FROM (SELECT EmpName, Qty, Item FROM #t) AS b
PIVOT(SUM(Qty) FOR Item IN([Dog],[Cat],[Goat],[Ram])) AS p
)
select empname, avg(dog) dog, avg(cat) cat, avg(goat) goat, avg(ram) ram
from ct
group by empname;
+---------+-----+-----+------+-----+
| empname | dog | cat | goat | ram |
+---------+-----+-----+------+-----+
| Abay | 0 | 0 | 5 | 0 |
+---------+-----+-----+------+-----+
| Carle | 2 | 11 | 0 | 0 |
+---------+-----+-----+------+-----+
| Jane | 6 | 0 | 8 | 3 |
+---------+-----+-----+------+-----+

Answer 6

SELECT EmpName
, [Dog]
, [Cat]
, [Goat]
, [Ram]
,(isnull(p.cat,0)+isnull(p.dog,0)+isnull(p.Goat,0)+isnull(p.Ram,0))/4.0 as average
FROM (SELECT EmpName, Qty, Item FROM #t) AS b
PIVOT(SUM(Qty) FOR Item IN([Dog],[Cat],[Goat],[Ram])) AS p