Select 1 letter Field MySQL

[cedricm]

Hello everybody,

I need your help for a small problem.
I have in my DB a category field imported from another solutions.
The DB is sructurd like that:
CategoryID, Description
A, System
AA, PC
AB, Notebook
AC, Handhelds.........
B, Storage
BA, HD
BB, DAT........

So there is my question,
I need to select all main Category first and then all other under category.
The main category is written with only 1 letter (A)
The sub-category with 2 letters (AA)

How need I to write my SQL sentence to select only 1 letter at first, and the the second sentence with 2 letters

PS: The letters are dynamics and never the same

Thanks for your help, Ced

[Danicek]

Select * From Table_name
Where CHAR_LENGTH(CategoryID) = 1

[cedricm]

Thank you!!