SQL Server select on aggregate function - sql

Question

I have a challenge regarding the use of an aggregate function in a where statement.
SELECT [tb_users].[id_user]
,[name]
,[Title]
,[FirstName]
,[LastName]
,[type]
,sum ([tb_LockAuditTrail].[price]) as SumPrice
FROM [SALTO_SPACE].[dbo].[tb_Users]
join [tb_LockAuditTrail]
on [tb_Users].[Cardcode] = [tb_LockAuditTrail].[Cardcode]
where [type] = 1
group by [tb_users].[id_user]
,[name]
,[Title]
,[FirstName]
,[LastName]
,[type]
order by [SumPrice] desc
This is running fine. From this dataset I want to select only the records above a certain SumPrice level. How do I do this?
I cannot use the alias SumPrice in the where statement because aliases are not allowed in where statements.
I also cannot use the aggregate SUM function in a where statement. So for now I don't see a solution other than filtering the result afterwards in an Excel sheet.

Answer 1

After the group by block and before the orderby block you write
HAVING sum ([tb_LockAuditTrail].[price]) > 100
Change the 100 accordingly
Even if HAVING weren't a thing, you don't have to use excel. Every SELECT creates a block of data that can be used like a table so you could wrap it all in brackets, give it an alias, and select from the query as if it were a table:
SELECT *
FROM
(
SELECT productcategory, sum(price) as sumprice
FROM products
GROUP BY productcategory
) summed
WHERE
summed.sumprice > 100
Get down with the notion that tables are only one kind of "block of data" that queries can use; you'll considerably increase your SQL querying ability if you keep in mind the fact FROM can use blocks of data from other sources such as queries and table valued functions. Here's another example:
SELECT *
FROM
products p
INNER JOIN
(
SELECT productcategory, sum(price) as sumprice
FROM products
GROUP BY productcategory
) sumcat
ON p.productcategory = sumcat.productcategory
INNER JOIN
(
SELECT warehouse, count(*) as sumprice
FROM products
GROUP BY warehouse
) countwh
ON p.warehouse = countwh.warehouse
WHERE
...
You can also use the WITH command, to alias a query so you can then use it like a table:
WITH
sumcat AS (
SELECT productcategory, sum(price) as sumprice
FROM products
GROUP BY productcategory
),
countwh as (
SELECT warehouse, count(*) as sumprice
FROM products
GROUP BY warehouse
)
--now use them like tables
SELECT *
FROM
products p
INNER JOIN sumcat s ON p.productcategory = s.productcategory
INNER JOIN countwh c ON p.warehouse = c.warehouse
This is one way how we can get every product detail but also the sum of all the prices in the category and the count of all the products in the various warehouses - perhaps pointless data but I'm demonstrating how you can use subqueries to generate blocks of data that can be joined to tables, and also each detail line can have a summary aspect too. Ordinarily you have to lose detail to generate summaries so the learning notions here are:
subqueries are blocks of data just like tables and can be joined just like tables
give everything an alias and use it
to get detail and summary together generate the summary and join it to the detail
a table can appear multiple times in a query and can be joined to itself even, so long as the two occurrences of the table have different aliases