Shrinking the Transaction Log in SQL Server 2005
Use the MS SQL Server Management Studio
EXEC sp_dboption 'XXX', 'trunc. log on chkpt.', 'TRUE'
CHECKPOINT
DBCC SHRINKFILE ('XXX_Log', TRUNCATEONLY)
EXEC sp_dboption 'XXX', 'trunc. log on chkpt.', 'FALSE'
GO
(replace XXX with the database name)


