is there a way to check query after parameters are applied?

Question

Consider below query , i am passing (--  double dash in username to bypass password)

SqlCommand cmd=new SqlCommand("Select * from users where username=@UserName and Password=@password",con );

Now, i am passing username as Sachin'-- and with password field empty.

 

According to me , the query now becomes 

Select * from users where username='Sachin'--' and Password=''

 As you can see, it seems like i am successfully able to bypaas Password , i just wanted to know how the query is constructed when parameters are used , cause obviously it prevents SQL injection.

 

Please take the same example and clearify.