【由浅入深学MySQL】之MySQL索引基础入门

-- 创建student表
CREATE TABLE `student` (
  `SId` int(10) NOT NULL AUTO_INCREMENT,
  `Sname` varchar(10) DEFAULT NULL,
  `Sage` int(255) DEFAULT NULL,
  `Ssex` varchar(10) DEFAULT NULL,
  PRIMARY KEY (`SId`)
) ENGINE=InnoDB AUTO_INCREMENT=17 DEFAULT CHARSET=utf8;

-- 添加数据
INSERT INTO `student` VALUES ('1', '赵雷', '23', '男');
INSERT INTO `student` VALUES ('2', '钱电', '22', '男');
INSERT INTO `student` VALUES ('3', '穷奇', '12', '男');
INSERT INTO `student` VALUES ('4', '饕鬄', '23', '男');
INSERT INTO `student` VALUES ('5', '周梅', '45', '女');
INSERT INTO `student` VALUES ('6', '吴兰', '12', '女');
INSERT INTO `student` VALUES ('7', '郑竹', '43', '女');
INSERT INTO `student` VALUES ('9', '张三', '33', '女');
INSERT INTO `student` VALUES ('10', '李四', '44', '女');
INSERT INTO `student` VALUES ('11', '李四', '24', '女');
INSERT INTO `student` VALUES ('12', '赵六', '54', '女');
INSERT INTO `student` VALUES ('13', '孙七', '23', '女');
INSERT INTO `student` VALUES ('14', '青龙', '12', '男');
INSERT INTO `student` VALUES ('15', '白虎', '34', '女');
INSERT INTO `student` VALUES ('16', '梼杌', '54', '男');

-- 为student表中姓名列创建一个普通索引
CREATE INDEX idx_name ON student(Sname);

-- 为student表中年龄列创建一个唯一索引
CREATE UNIQUE INDEX idx_age ON student(Sage);

-- 查看student表中的索引
SHOW INDEX FROM student;

-- 删除student表中的idx_score索引
DROP INDEX idx_score ON student;

-- 查看student表中的索引
SHOW INDEX FROM student;

-- 创建product商品表
CREATE TABLE product(
  id INT PRIMARY KEY AUTO_INCREMENT,  -- 商品id
  NAME VARCHAR(10),                   -- 商品名称
  price INT                           -- 商品价格
);

-- 定义存储函数，生成长度为10的随机字符串并返回
DELIMITER $

CREATE FUNCTION rand_string() 
RETURNS VARCHAR(255)
BEGIN
DECLARE big_str VARCHAR(100) DEFAULT 'abcdefghijklmnopqrstuvwxyzABCDEFGHIGKLMNOPQRSTUVWXYZ';
DECLARE small_str VARCHAR(255) DEFAULT '';
DECLARE i INT DEFAULT 1;

WHILE i <= 10 DO
SET small_str =CONCAT(small_str,SUBSTRING(big_str,FLOOR(1+RAND()*52),1));
SET i=i+1;
END WHILE;

RETURN small_str;
END$

DELIMITER ;



-- 定义存储过程，添加100万条数据到product表中
DELIMITER $

CREATE PROCEDURE pro_test()
BEGIN
DECLARE num INT DEFAULT 1;

WHILE num <= 1000000 DO
INSERT INTO product VALUES (NULL,rand_string(),num);
SET num = num + 1;
END WHILE;
END$

DELIMITER ;

-- 调用存储过程
CALL pro_test();


-- 查询总记录条数
SELECT COUNT(*) FROM product;



-- 查询product表的索引
SHOW INDEX FROM product;

-- 查询name为OkIKDLVwtG的数据   (0.049)
SELECT * FROM product WHERE NAME='OkIKDLVwtG';

-- 通过id列查询OkIKDLVwtG的数据  (1毫秒)
SELECT * FROM product WHERE id=999998;

-- 为name列添加索引
ALTER TABLE product ADD INDEX idx_name(NAME);

-- 查询name为OkIKDLVwtG的数据   (0.001)
SELECT * FROM product WHERE NAME='OkIKDLVwtG';


/*
范围查询
*/
-- 查询价格为800~1000之间的所有数据 (0.052)
SELECT * FROM product WHERE price BETWEEN 800 AND 1000;

/*
排序查询
*/
-- 查询价格为800~1000之间的所有数据,降序排列  (0.083)
SELECT * FROM product WHERE price BETWEEN 800 AND 1000 ORDER BY price DESC;

-- 为price列添加索引
ALTER TABLE product ADD INDEX idx_price(price);

-- 查询价格为800~1000之间的所有数据 (0.011)
SELECT * FROM product WHERE price BETWEEN 800 AND 1000;

-- 查询价格为800~1000之间的所有数据,降序排列  (0.001)
SELECT * FROM product WHERE price BETWEEN 800 AND 1000 ORDER BY price DESC;