SQL Update statement with aggregate count - sql-server

Question

I am getting the following error
Subquery returned more than 1 value. This is not permitted when the
subquery follows =, !=, <, <= , >, >= or when the subquery is used as
an expression.
For this query:
UPDATE b
SET b.Products = (SELECT COUNT(pf.Product_Family_ID)
FROM Product_Families pf
INNER JOIN Products p ON pf.Product_Family_ID = p.Product_Family_ID
INNER JOIN Brands b2 on pf.BrandID = b2.Brand_ID
WHERE
pf.Discontinued = 0
AND pf.Live = 0
AND p.Inventory > 0
AND pf.Brand <> ''
GROUP BY
b2.Brand, b2.Brand_ID)
FROM Brands b
INNER JOIN Product_Families pf2 ON b.Brand_ID = pf2.BrandID
WHERE
b.Brand_ID = pf2.BrandID
I know I am missing just a little something. Thanks for the help.

Answer 1

You can't assign a non-scalar value to a scalar value. Your subquery could return a set of tuples because you are asking for a COUNT on each group. Run the subquery by itself:
(Select COUNT(pf.Product_Family_ID)
FROM Product_Families pf
INNER JOIN Products p ON pf.Product_Family_ID = p.Product_Family_ID
INNER JOIN Brands b2 on pf.BrandID = b2.Brand_ID
WHERE
pf.Discontinued = 0
AND
pf.Live = 0
AND
p.Inventory > 0
AND
pf.Brand <> ''
GROUP BY b2.Brand, b2.Brand_ID)
and you will see what it returns. You probably want a count of all the records in the subquery: take out the groupings.

Answer 2

As #nicomp said, Your subquery will return more than one result so just filter out the result to specific brands.
Try this:
UPDATE b
SET b.Products = Select number (SELECT COUNT(pf.Product_Family_ID) as number, b2.Brand_ID
FROM Product_Families pf
INNER JOIN Products p ON pf.Product_Family_ID = p.Product_Family_ID
INNER JOIN Brands b2 on pf.BrandID = b2.Brand_ID
WHERE
pf.Discontinued = 0
AND pf.Live = 0
AND p.Inventory > 0
AND pf.Brand <> ''
GROUP BY
b2.Brand, b2.Brand_ID)
Where Brand_ID = b.Brand_ID
FROM Brands b
INNER JOIN Product_Families pf2 ON b.Brand_ID = pf2.BrandID
WHERE
b.Brand_ID = pf2.BrandID
This is not optimized but this will fix your error.

Answer 3

Thank you for all the help, here is the solution that I used.
IF OBJECT_ID('tempdb..#Temp') IS NOT NULL
/*Then it exists*/
DROP TABLE #Temp
SELECT * INTO #Temp FROM (SELECT
b.Brand_ID,
b.Brand,
COUNT(pf.Product_Family_ID) PFBrandCount FROM Product_Families pf
INNER JOIN Products p ON pf.Product_Family_ID = p.Product_Family_ID
INNER JOIN Brands b on pf.BrandID = b.Brand_ID
WHERE
pf.Discontinued = 0
AND
pf.Live = 0
AND
p.Inventory > 0
AND
pf.Brand <> ''
Group BY b.Brand, b.Brand_ID) data
Update b SET Products = #Temp.PFBrandCount
FROM BRANDS b
INNER JOIN #Temp ON b.Brand_ID = #Temp.Brand_ID
DROP TABLE #Temp