Updating a table row with random number fails - mysql

Question

I am using a while loop in a stored procedure to update each row of my table but the update value remains the same for all rows.For instance,in my table the generated number is 2266 for all rows instead of a unique digit.
My stored procedure looks like this
DELIMITER ;;
CREATE PROCEDURE lesrows()
BEGIN
DECLARE n INT DEFAULT 0;
DECLARE i INT DEFAULT 0;
DECLARE lesrand INT DEFAULT 0;
SELECT COUNT(*) FROM students INTO n;
select(FLOOR(2000 + RAND() * (3000 - 2000) )) into lesrand;
SET i=0;
WHILE i<n DO
UPDATE students set student_number= lesrand;
SET i = i + 1;
END WHILE;
End;
;;
call lesrows();
Why is it inserting a constant number for all rows instead of a unique number for every row?.

Answer 1

The while statement sets the whole table's student_number's the lesrand on every single iteration. You want a new random number of each iteration (inside the loop) and you want to select students one-by-one using WHERE with your variable i
Something like this:
SET i=0;
WHILE i<n DO
select(FLOOR(2000 + RAND() * (3000 - 2000) )) into lesrand;
UPDATE students set student_number= lesrand WHERE student_ID = i;
SET i = i + 1;
END WHILE;

Answer 2

I haven't tested it, but it looks like lesrand is only assigned once. Have you tried moving select(FLOOR(2000 + RAND() * (3000 - 2000) )) into lesrand; into the while loop like this:
DELIMITER ;;
CREATE PROCEDURE lesrows()
BEGIN
DECLARE n INT DEFAULT 0;
DECLARE i INT DEFAULT 0;
DECLARE lesrand INT DEFAULT 0;
SELECT COUNT(*) FROM students INTO n;
SET i=0;
WHILE i<n DO
select(FLOOR(2000 + RAND() * (3000 - 2000) )) into lesrand;
UPDATE students set student_number= lesrand;
SET i = i + 1;
END WHILE;
End;
;;
call lesrows();
And why are you using a stored procedure. Wouldn't UPDATE students SET student_number = FLOOR(2000 + RAND() * (3000 - 2000)) have the same result?