Sign-in Failure Rate by Tenant Domain

SQL practice question · Medium · Strings · Microsoft

Extract the tenant domain from each `upn` (user principal name): everything after the '@', trimmed and lowercased. Rows whose upn has no '@' are ignored. `success` is 1 for a successful sign-in and 0 for a failure. Return `domain`, `signins`, `failed`, `failure_pct` = ROUND(100.0 * failed / signins, 1). Order by `failure_pct` DESC, then `domain`.

Table: signins

Schema of signins
ColumnType
signin_idINTEGER
upnTEXT
successBOOLEAN
Sample rows of signins
signin_idupnsuccess
1asha@contoso.com1
2ben@contoso.com0
3Chen@Contoso.com1
4dev@fabrikam.io0
5eli@fabrikam.io0
6fay@fabrikam.io1
7svc-backup0
Expected output on the sample data
domainsigninsfailedfailure_pct
fabrikam.io3266.7
contoso.com3133.3

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