EXEC sp_MSforeachtable @command1 = "DELETE FROM ?" EXEC sp_MSforeachtable @command1 = "TRUNCATE TABLE ?"
sp_MSforeachtable is a hidden Stored Procedure in sql server, that will execute for all the tables for database (no rollback)
@command1 is variable which will run against each table for connected database.
Whatever you will write in the double quotes, that will be act as a command for each table, where '?' is the name of the table.
Word of caution. Make sure execute these commands on test Database before actually executing in the desired database
Note: This post is from my old blog dated Thursday, February 2011, that unfortunately no longer exist