问题
When querying for the last backup_finish_date with the following query (from SQL Server: how to query when the last transaction log backup has been taken?):
SELECT d.name,
d.recovery_model_desc,
MAX(b.backup_finish_date) AS backup_finish_date
FROM master.sys.databases d
LEFT OUTER JOIN msdb..backupset b
ON b.database_name = d.name
AND b.type = 'L'
GROUP BY d.name, d.recovery_model_desc
ORDER BY backup_finish_date DESC
The backup_finish_date for all my databases is null, this is for DBs with a recovery mode of BULK_LOGGED, FULL or SIMPLE.
Does this imply that none of these databases has had their transaction log backed up (as suggested by the title of the linked question)?
回答1:
Yes, You are correct. If your backup_finish_date is null means it was never backed up. However, msdb..backupset can be modified/tempered. You can check last backup of the database with backup type.
SELECT d.name,
d.recovery_model_desc,
b.type, -- type of backup
MAX(b.backup_finish_date) AS backup_finish_date
FROM master.sys.databases d
LEFT OUTER JOIN msdb..backupset b
ON b.database_name = d.name
GROUP BY d.name, d.recovery_model_desc, b.type
ORDER BY backup_finish_date DESC
type Can be:
D = Database OR Full
I = Differential database
L = Log
F = File or filegroup
G =Differential file
P = Partial
Q = Differential partial
Can be NULL.
Refer MSDN
来源：https://stackoverflow.com/questions/40050221/sql-server-what-exactly-is-the-backup-finish-date-in-master-sys-databases