Here's something I saved a while back. This of course isn't EVERYTHING, but most extended chords would be built off these. And of course the relative minor is the 6th chord in the key, and would use the same chords:
12 KEYS IN MUSIC:
1 - A = A-Bm-C#m-D-E7-F#m-G#m7b5
2 - A#/Bb = Bb-Cm-Dm-Eb-F7-Gm-Am7b5
3 - B = B-C#m-D#m-E-F#7-G#m-A#m7b5
4 - C = C-Dm-Em-F-G7-Am-Bm7b5
5 - Db/C# = Db-Ebm-Fm-Gb-Ab7-Bbm-Cm7b5
6 - D = D-Em-F#m-G-A7-Bm-C#m7b5
7 - Eb/D# = Eb-Fm-Gm-Ab-Bb7-Cm-Dm7b5
8 - E = E-F#m-G#m-A-B7-C#m-D#m7b5
9 - F = F-Gm-Am-Bb-C7-Dm-Em7b5
10 - F#/Gb = F#-G#m-A#m-B-C#7-D#m -E#[F]mtb5
11 - G = G-Am-Bm-C-D7-Em-F#m7b5
12 - Ab/G# = Ab-Bbm-Cm-Db-Eb7-Fm-G#m7b5-Ab
Anyone of these 12 Keys can be used to write music in, are read left to right, and all 12 of these Keys have:
1. 7 Chords--2 of which are Major, 3 - Minor, 1 - Dom. [i.e. G7, D7, C7...etc.], and a 1- Minor7b5 Chord in each of them. Verify this now.
2. These 7 Chords will ALWAYS sound good when played together. In any order.
3. A single Major Scale can be used to solo over all 7 of them--regardless of the fact that they are Major & Minor..etc.. For example for the 'Key of D,' we have these 7 Chords:
6 - D = D-Em-F#m-G-A7-Bm-C#m7b5
And, the 'D' Major Scale can be used so Solo over ALL of it's 7 Chords.