Total column in a pivot example - sql

Question

check here for background if needed:
Pivoting a table with parametrization
We have 3 tables.
tid_color - parametrization table
--------------------------
ID ColorDescription
--------------------------
1 Green
2 Yellow
3 Red
-------------------------
tid_car - parametrization table
--------------------------
ID CARDescription
-------------------------
1 Car X
2 Car Y
3 Car Z
--------------------------
table_owners_cars
------------------------------------------------
ID CarID ColorID Owner
------------------------------------------------
1 1 1 John
2 1 2 Mary
3 1 3 Mary
4 1 3 Giovanni
5 2 2 Mary
6 3 1 Carl
7 1 1 Hawking
8 1 1 Fanny
------------------------------------------------
CarID is FOREIGN KEY to tid_car
ColorId is FOREIGN KEY to tid_color
If we code:
SELECT tcar.CarDescription, tco.ColorDescription, Count(*) as Total
FROM table_owners_cars tocar
LEFT JOIN tid_color tco ON tco.Id = tocar.ColorId
LEFT JOIN tid_Car tcar ON tcar.Id = tocar.CarId
GROUP BY CarDescription, ColorDescription
it results as:
Id CarDescription ColorDescription Total
1 CarX Green 3
2 CarX Yellow 1
3 CarX Red 1
4 CarY Yellow 1
5 CarZ Green 1
I want to pivot exactly as follows:
---------------------------------------------
Id Car Green Yellow Red Total
---------------------------------------------
1 CarX 3 1 1 5
2 CarY 0 1 0 1
3 CarZ 1 0 0 1
---------------------------------------------
Now:
we want to count the total for each row in a particular column of the table_owners_cars and this value is close to total like we see in the last column (between parenthesis). There are CarX WITH a NULL for the colorID (same can happen with the other Car) and we want to know all the number of carX, carY, CarZ (with and without (=null or 0) assigned ColorId
---------------------------------------------------
Id Car Green Yellow Red Violet Total
---------------------------------------------------
1 CarX 3 1 1 0 5 (40)
2 CarY 0 1 0 0 1 (35)
3 CarZ 1 0 0 0 1 (4)
---------------------------------------------------
DESIRED TABLE
One try with the code (very similar to one provided in the aforementioned hyperlink):
SELECT pvt.CarID, tc.Description AS Car, CONCAT (' [1] as 'Green', [2] as 'Yellow', [3] as 'Red', [1]+[2]+[3] as 'total'', '(', count(*), ')' )
FROM
(SELECT CarID, colorId
FROM table_owners_cars tocar
) p
PIVOT
(
COUNT (ColorId)
FOR ColorId IN ( [1], [2], [3])
) AS pvt
INNER JOIN tid_car tc ON pvt.CarId=tc.Id
group by p.Car
this does not work. single quotes are also a nightmare with concat. Thanks in advance.

Answer 1

I just find these queries easier to do with conditional aggregation:
SELECT CarId, Description,
SUM(CASE WHEN color = 'Green' THEN 1 ELSE 0 END) as Green,
SUM(CASE WHEN color = 'Yellow' THEN 1 ELSE 0 END) as Yellow,
SUM(CASE WHEN color = 'Red' THEN 1 ELSE 0 END) as Red,
SUM(CASE WHEN color IN ('Green', 'Yellow', 'Red') THEN 1 ELSE 0 END) as total_gyr,
COUNT(*) as total
FROM table_owners_cars tocar
GROUP BY CarId, Description;
I see no reason to combine the two totals into a single string column -- as opposed to having them in separate integer columns. But, you can combine them if you want.