key signature
D♭ major
D♭1E♭2F3G♭4A♭5B♭6C7
5 flats, written B♭ E♭ A♭ D♭ G♭
The chords that live in it
D♭degree 1 · majorE♭mdegree 2 · minorFmdegree 3 · minorG♭degree 4 · majorA♭degree 5 · majorB♭mdegree 6 · minorCdimdegree 7 · diminished
Built by stacking thirds inside the scale and asking what quality comes out, rather than from a table of roman numerals.
What is true of it
D♭ major has 5 flats.
They are written in this order, always: B♭ E♭ A♭ D♭ G♭.
Its notes are D♭, E♭, F, G♭, A♭, B♭ and C.
Relative: B♭ minor has the same 5 flats. Parallel: D♭ minor has 8 flats, which is why changing mode changes the signature by three.
Every key
C♭ majorG♭ majorA♭ majorE♭ majorB♭ majorF majorC majorG majorD majorA majorE majorB majorF♯ majorC♯ majorA♭ minorE♭ minorB♭ minorF minorC minorG minorD minorA minorE minorB minorF♯ minorC♯ minorG♯ minorD♯ minorA♯ minor