1) The first is by using the trill key with the right index finger.
1) Another technique is to use alternative fingerings which include:
- Half-hole the B-flat key or the C key with the right thumb
- Use the whisper key (on some instruments) with the left index finger
- Use the side key with the left index finger
3) The last technique is known as "pinching" which involves adjusting the embouchure or lip position while playing the D note to produce the D#.