Sorry if this is too basic a question for this list, but I don't fully get how to use aggregates (sum()) and group-by together. I'm trying to get a list of transactions where the total for a given account exceeds a given number. I'm not sure an example is needed, but if so, consider this simplified data:
accountid. name
1 bill
2. james
3 sarah
4 carl
transaction
id. amount. accountid. name
1. 50. 1 bill
2. 25. 2 james
3 35 4 carl
4. 75. 1 bill
5 25. 1 bill
6 50 3 sarah
results wanted-all transactions where account total >= 50
id. amount. accountid. name
1. 50. 1 bill
3. 75. 1 bill
4 25. 1 bill
5 50 3 sarah
You have 2 concepts here - identify the accounts with a total over 50 and then show the transactions for those accounts. I prefer CTEs here because they allow for better understanding (to me) of the steps involved. A subquery would work here as well.
with accounts_over_total as (
select accountid from transactions where sum(amount) >= 50 group by accountid)
select transactions.* from transactions join accounts_over_total on transactions.accountid = accounts.accountid
John
I've tried to understand how to use GROUP BY and HAVING, but the penny won't drop. I keep getting errors saying that all columns in the SELECT have to also be in the GROUP BY, but nothing I've done seems to produce the correct results. I think because the GROUP BY contains multiple columns, so each row is treated as a group. It also is difficult to parse out since in the real world, many more tables and columns are involved.