當測試SQL效能時，需要使用儲存函式造資料

建立隨機字串，引數為字串的長度

DROP FUNCTION IF EXISTS rand_string;
delimiter $$
CREATE FUNCTION rand_string (n INT) RETURNS VARCHAR (255)
BEGIN
    DECLARE chars_str VARCHAR (100) DEFAULT 'qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM' ;
    DECLARE return_str VARCHAR (255) DEFAULT
 
 '' ;
    DECLARE i INT DEFAULT 0 ;
    WHILE i < n DO
        SET return_str = concat(return_str,substring(chars_str,floor(1 + rand() *52),1) );
        SET i = i + 1 ;
    END WHILE; 
    RETURN return_str;
END$$

建立隨機數，引數為隨機數的位數

DROP FUNCTION IF EXISTS rand_num;
delimiter $$
CREATE FUNCTION rand_num (n INT
 
) RETURNS INT (15)
BEGIN
    DECLARE i INT DEFAULT 1 ;
    DECLARE total INT DEFAULT 10 ;
    DECLARE random INT DEFAULT 0 ;
    WHILE i < n DO
        SET total = total * 10 ;
        SET i = i + 1 ;
    END WHILE;
    SET random = FLOOR(RAND() * total) ; RETURN random ;
END$$

批量生成隨機資料插入表

DROP PROCEDURE
 
 IF EXISTS student_insert_procedure;
CREATE PROCEDURE student_insert_procedure (count INT)
BEGIN
    DECLARE n INT DEFAULT 0;
    DECLARE days INT;#當前日期加上的隨機天數
    WHILE n < count DO
        SET days = rand_num (3);
        INSERT INTO student (`id`, `stuname`, birthday)VALUES(rand_num (5),rand_string (15),DATE_ADD(CURDATE(), INTERVAL days DAY));
        SET n = n + 1;
    END WHILE;
COMMIT;
END
call student_insert_procedure(10);