Great! Now, there is an alternative CTE syntax where we define the columns explicitly:
WITH SomeName (CteColumns) AS (
In other words, we now have two pairs of parentheses. First, we provide the names of columns that our CTE will have. Second, we define the actual CTE based on the columns we provided.
WITH ProjectRevenue (Id, SumAmount) AS (
INNER JOIN Donation
ON Donation.ProjectId = Project.Id
GROUP BY Project.Id
Defining the columns this way is not required. Why would we use it? For one thing, it increases the readability of your query. For another, while simple columns inside CTEs don't require aliases, those containing aggregates and other function results do. Columns like
COUNT(ProjectId) must be given names so that you can refer to them outside the CTE. One way to create aliases is to use the keyword
AS, just as we did previously. Another way is to provide a list of columns. Either method is fine, but if you use neither an error will occur.