I need help with reading user input

Question

Hi there, I have the following sql query:
select v.veh_vin, v.veh_make, v.veh_model, v.veh_regonumber, c.cond_desc
from vehicle v, condition c
where v.cond_code = c.cond_code and v.br_no = &branch_number
order by v.veh_make, v.veh_model;
The query compiles fine, but when I'm prompted to input the value for "&branch_number", I get an error stating "invalid identifier". I make I input the value correctly, but I still keep getting an error. Can anyone tell me what I'm doing wrong? (v.br_no is a CHAR(4 byte) datatype, if this helps.)
On an unrelated note, what's the difference between using only one ampersand, compared to using two ampersands? (ie. what's the difference between "&branch_number" and "&&branch_number"?)

Answer 1

Are you providing a char-value? That is are you enclosing it between single quotes?
You could also do this:
select v.veh_vin, v.veh_make, v.veh_model, v.veh_regonumber, c.cond_desc
from vehicle v, condition c
where v.cond_code = c.cond_code and v.br_no = '&branch_number'
order by v.veh_make, v.veh_model;Which prevents you from having to provide the quotes every time.
The double ampersand will prevent being prompted twice (or as many times as the variable is used inside the query).
Eg.
select *
from dual
where &i = &i
/Will prompt you twice to provide the value for i. Whereas:
select *
from dual
where &&i = &&i
/will only prompt you once.
Toon