DDL

CREATE TABLE student (id INT PRIMARY KEY AUTO_INCREMENT,creatDate DATE NOT NULL,userName VARCHAR(255) NOT NULL,phone VARCHAR(15) NOT NULL,age INT NOT NULL,sex ENUM('M', 'F', 'O') NOT NULL,  -- 假设'M'代表男，'F'代表女，'O'代表其他introduce TEXT
);

生成20万随机数据的存储过程

DELIMITER //
CREATE PROCEDURE InsertRandomStudents()
BEGINDECLARE i INT DEFAULT 0;WHILE i < 200000 DOINSERT INTO student (creatDate, userName, phone, age, sex, introduce) VALUES (-- 随机日期（过去10年内）DATE_SUB(CURDATE(), INTERVAL FLOOR(RAND() * 3650) DAY),-- 随机用户名（假设格式为“user_XXXX”，其中XXXX是随机数）CONCAT('user_', FLOOR(RAND() * 10000)),-- 随机电话号码（假设格式为“13XXXXXXXXX”，其中X是随机数字）CONCAT('13', LPAD(FLOOR(RAND() * 999999999), 9, '0')),-- 随机年龄（18到30岁）FLOOR(RAND() * (30 - 18 + 1)) + 18,-- 随机性别（M, F, O中的一个）ELT(1 + FLOOR(RAND() * 3), 'M', 'F', 'O'),-- 随机介绍（假设为“This is a random introduction.” 或 NULL）IF(RAND() > 0.5, 'This is a random introduction.', NULL));SET i = i + 1;END WHILE;
END //
DELIMITER ;CALL InsertRandomStudents();select count(*)from student;

 生成中文，添加索引

select char(34567);
select * from student where userName='user512591';
-- 无索引0.091s
-- 索引后0.03s

if满足特定需求

DELIMITER //
CREATE PROCEDURE InsertStudent(IN p_userName VARCHAR(255),IN p_age INT,IN p_introduce TEXT
)
BEGIN-- 检查输入的数据不为空IF p_userName IS NULL OR p_age IS NULL OR p_introduce IS NULL THENSIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Input values must not be NULL';END IF;-- 检查userName不是以张、王、李、兆开头IF LEFT(p_userName, 1) = '张' OR LEFT(p_userName, 1) = '王' OR LEFT(p_userName, 1) = '李' OR LEFT(p_userName, 1) = '兆' THENSIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'userName must not start with 张, 王, 李, or 兆';END IF;-- 插入数据，其中creatDate、phone、sex是随机生成的INSERT INTO student (creatDate, userName, phone, age, sex, introduce) VALUES (-- 随机日期（当前日期之前的随机天数）DATE_SUB(CURDATE(), INTERVAL FLOOR(RAND() * 3650) DAY),-- 传入的用户名p_userName,-- 随机电话号码（假设格式为“13XXXXXXXXX”，其中X是随机数字）CONCAT('13', LPAD(FLOOR(RAND() * 999999999), 9, '0')),-- 传入的年龄p_age,-- 随机性别（M, F, O中的一个）ELT(1 + FLOOR(RAND() * 3), 'M', 'F', 'O'),-- 传入的介绍p_introduce);
END //
DELIMITER ;CALL InsertStudent('SampleName', 25, 'This is a sample introduction.');

case when语句

SELECT id,userName,age,sex,CASE WHEN sex = 'M' THEN '男性'WHEN sex = 'F' THEN '女性'WHEN sex = 'O' THEN '泰国人'ELSE '未知' -- 可选，为了处理未来可能出现的其他性别代码END AS display_sex
FROM student
LIMIT 2000;