MYSQL output in tree format OR Adding level (Parent-Child)

Question

Below is what I have in my table.

myTable

++++++++++++++++++++
Parent   +  Child
++++++++++++++++++++
  C1     +    G1
  C1     +    G2
  C1     +          


        

Answer 1

first Create Recursive function for calc level.

function fn_CalcLevel(int @ID) 
As Begin
  Declare @ParentID int
  Select @ParentID = ParentID From Table1 where ID = @ID

  IF (@ParentID IS NULL) Return 1 Else Return 1+fn_CalcLevel(@ParentID)
End

then Create your Query Such as Below

Select *, fn_CalcLevel(Table1.ID) as Level
From Table1