You can clean your database by executing one single procedure.
There are two tables "Client" and "Student"which have data
Now, create the following procedure
Create PROCEDURE sp_DeleteAllData
AS
EXEC sp_MSForEachTable 'ALTER TABLE ? NOCHECK CONSTRAINT ALL'
EXEC sp_MSForEachTable 'ALTER TABLE ? DISABLE TRIGGER ALL'
EXEC sp_MSForEachTable 'DELETE FROM ?'
EXEC sp_MSForEachTable 'ALTER TABLE ? CHECK CONSTRAINT ALL'
EXEC sp_MSForEachTable 'ALTER TABLE ? ENABLE TRIGGER ALL'
EXEC sp_MSFOREACHTABLE 'SELECT * FROM ?'
GO
and execute this procedure if want to clean the database by the following command
exec sp_DeleteAllData
All record will be delete from each and every table by this procedure.