SQL: Billing Software Report $2$

You are working on a billing application and need to get a list of customers with their transaction transcripts.

The result should have the following columns: iban $/$ transactions $/$ total.

iban$-$client's IBAN number

transactions $-$ list of transaction amount records for a specific IBAN:

Record is a transaction amount

Records are separated by the sign of the amount of the transaction surrounded by a single space. See 'Expected Output' for an example.

Records are sorted in ascending order of $dt$

total $-$ the total amount of all $\backslash$Yansactions for a specific IBAN

The result should be sorted in descending order by total.