sum of two columns assigned to a condition - sql

Question

hi im trying to get the total of two columns stored to a name then get a condition but i having error on the 'Rebound' name on line 3
the offreb and defreb has a integer type and some values are stored as 0 (zero)
SELECT team, CONCAT(firstname,' ',lastname) AS name, SUM(offreb + defreb) AS Rebounds
FROM boxscore
WHERE round = 'Finals' AND game = 7 AND Rebounds > 0
ORDER BY team, Rebounds;

Answer 1

You want to filter by column in the WHERE clause which is not yet calculated when the WHERE clause is executed. You can use a sub-query or having.
It should be something like this:
SELECT team, CONCAT(firstname,' ',lastname) AS name, SUM(offreb + defreb) AS Rebounds
FROM boxscore
WHERE round = 'Finals' AND game = 7
GROUP BY team, CONCAT(firstname,' ',lastname)
HAVING SUM(offreb + defreb) > 0
ORDER BY team, Rebounds;

Answer 2

Here using HAVING clause solves your issue.
If a table has been grouped using GROUP BY, but only certain groups
are of interest, the HAVING clause can be used, much like a WHERE
clause, to eliminate groups from the result.
Official postgres docs
SELECT
team,
CONCAT(firstname,' ',lastname) AS name,
SUM(offreb + defreb) AS "Rebounds"
FROM
boxscore
WHERE
round = 'Finals' AND game = 7
GROUP BY
team,
CONCAT(firstname,' ',lastname)
HAVING
SUM(offreb + defreb) > 0
ORDER BY
team, "Rebounds";
Note that you cannot use column alias in WHERE and GROUP BY clause, but can be used in ORDER BY clause and wrap double quotes to preserve case-sensitivity.