The key of D major
D E F♯ G A B C♯
2 sharps: F♯ C♯. Relative minor: The key of B minor.
The triads of the key
I
D | ii
Em | iii
F♯m | IV
G | V
A | vi
Bm | vii°
C♯° |
The seventh chords
Imaj7
Dmaj7 | ii7
Em7 | iii7
F♯m7 | IVmaj7
Gmaj7 | V7
A7 | vi7
Bm7 | viiø7
C♯m7♭5 |
D major scale
Open it in the app: 6. Harmony, in D