I found this very helpful the other day. Feel free to use it.

USE [Master]
DECLARE @Database nvarchar(150)
DECLARE @SQLQuery nvarchar(max)
DECLARE dbCursor CURSOR
FOR
 SELECT Name FROM sys.databases
OPEN dbCursor

FETCH NEXT FROM dbCursor INTO @Database

WHILE @@FETCH_STATUS = 0
BEGIN

 SET @SQLQuery = 'BACKUP LOG ' + @Database + ' WITH TRUNCATE_ONLY 
 DBCC SHRINKDATABASE(' + @Database + ', TRUNCATEONLY)'
 EXEC (@SQLQuery)

 FETCH NEXT FROM dbCursor INTO @Database 
 
END

CLOSE dbCursor
DEALLOCATE dbCursor