How can you implement custom sort on SQL column?

Question

 How can you implement custom sort on SQL column?

Based on

1. Small case, Caps and then number.

2. Caps, small case then number

 

Considering following table with one column and values given.

 

TestData table

 

Data 

A

b

a

G

H

1

s

3

4

9

 

Looking for simple approach.