Possible to do a delete with a HAVING clause?

Question

I want to do something like below:

DELETE UserPredictions
  GROUP BY UserId
  HAVING COUNT(*) < 500

But I\'m getting a syntax error. Is

Answer 1

You can do so much with using row_number() OVER (partition by ) and CTE's, but only if your RDBMS supports it.

Example:

WITH CTE AS 
(
    SELECT UserId,
    ROW_NUMBER() OVER (PARTITION BY UserId ORDER BY UserId) AS rowcount    
    FROM UserPredictions
)
DELETE FROM CTE
WHERE rowcount < 500

Additional info about the row count function:

https://docs.microsoft.com/en-us/sql/t-sql/functions/row-number-transact-sql?view=sql-server-2017