Assigning value to a variable.

Question

i have one doubt.
we can assign value to a variable either in declaration section or in exectuion section.
so please explain when and wherer should we assign value to a variable.
thank you very much.

Answer 1

I think the best way to look at it is...
If you don't want your variable(s) to have default values that are NULL, assign a value in the declaration section, otherwise assign it where you feel like.
If you take an example of:
declare
  v_sum number := 0; -- default variable to 0
  cursor cur_test is
begin
  for i in cur_test
  loop
    v_sum := 0; -- set variable to 0 before the loop
    loop
      exit when .. some condition ..
      v_sum := v_sum + ..
    end loop;
  end loop;
end;
/.. we have a need to set the variable v_sum to 0 before each iteration of the internal loop, so there's little point in having it defaulted to 0 in the declaration section, hence I wouldn't typically default it there and would typically have the code as..
declare
  v_sum number; -- no point in defaulting it
  cursor cur_test is
begin
  for i in cur_test
  loop
    v_sum := 0; -- set variable to 0 before the loop
    loop
      exit when .. some condition ..
      v_sum := v_sum + ..
    end loop;
  end loop;
end;
/It all depends on what you're doing and what seems the most logical or preferred option.
Defaulting values in the declaration section can let you see clearly what the starting values are for things, but only if you really need to do it.