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G-4385: Never use a cursor for loop to check whether a cursor returns data.

Major

Efficiency

Reason

You might process more data than required, which leads to bad performance.

Example (bad)

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declare
   l_employee_found boolean := false;
   cursor c_employees is
      select employee_id,last_name
        from employees;
begin
   <<check_employees>>
   for r_employee in c_employees
   loop
      l_employee_found := true;
   end loop check_employees;
end;
/

Example (good)

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declare
   l_employee_found boolean := false;
   cursor c_employees is
      select employee_id,last_name
        from employees;
   r_employee       c_employees%rowtype;
begin
   open c_employees;
   fetch c_employees into r_employee;
   l_employee_found := c_employees%found;
   close c_employees;
end;
/