SQL Server backup results

SELECT a.name, b.type, DATEDIFF(MINUTE,b.backup_start_date , b.backup_finish_date),
b.backup_start_date ,
b.backup_finish_date
FROM master..sysdatabases a
LEFT OUTER JOIN msdb..backupset b ON a.name = b.database_name
WHERE DATEPART(DW,b.backup_start_date) IN (6, 7)
AND b.type NOT IN ( 'L', 'I')