feat: 更新 Mysql 示例

dependabot/maven/codes/javadb/elasticsearch/elasticsearch7/com.fasterxml.jackson.core-jackson-databind-2.12.7.1
dunwu 2023-06-27 23:11:19 +08:00
parent 651a6dbac0
commit d9253230f0
6 changed files with 180 additions and 33 deletions

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@ -1,3 +1,3 @@
# 源码说明
> 本目录代码为 [《SQL 必知必会》](https://item.jd.com/11232698.html) 部分示例源码
> 本目录代码为 [《SQL 必知必会》](https://book.douban.com/subject/35167240/) 部分示例源码

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@ -72,25 +72,25 @@ CREATE TABLE vendors (
-- Define primary keys
-- -------------------
ALTER TABLE customers
ADD PRIMARY KEY (cust_id);
ADD PRIMARY KEY (cust_id);
ALTER TABLE orderitems
ADD PRIMARY KEY (order_num, order_item);
ADD PRIMARY KEY (order_num, order_item);
ALTER TABLE orders
ADD PRIMARY KEY (order_num);
ADD PRIMARY KEY (order_num);
ALTER TABLE products
ADD PRIMARY KEY (prod_id);
ADD PRIMARY KEY (prod_id);
ALTER TABLE vendors
ADD PRIMARY KEY (vend_id);
ADD PRIMARY KEY (vend_id);
-- -------------------
-- Define foreign keys
-- -------------------
ALTER TABLE orderitems
ADD CONSTRAINT fk_orderitems_orders FOREIGN KEY (order_num) REFERENCES orders(order_num);
ADD CONSTRAINT fk_orderitems_orders FOREIGN KEY (order_num) REFERENCES orders(order_num);
ALTER TABLE orderitems
ADD CONSTRAINT fk_orderitems_products FOREIGN KEY (prod_id) REFERENCES products(prod_id);
ADD CONSTRAINT fk_orderitems_products FOREIGN KEY (prod_id) REFERENCES products(prod_id);
ALTER TABLE orders
ADD CONSTRAINT fk_orders_customers FOREIGN KEY (cust_id) REFERENCES customers(cust_id);
ADD CONSTRAINT fk_orders_customers FOREIGN KEY (cust_id) REFERENCES customers(cust_id);
ALTER TABLE products
ADD CONSTRAINT fk_products_vendors FOREIGN KEY (vend_id) REFERENCES vendors(vend_id);
ADD CONSTRAINT fk_products_vendors FOREIGN KEY (vend_id) REFERENCES vendors(vend_id);

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@ -1,8 +1,8 @@
/**
* Mysql
* @author Zhang Peng
* @date 2018/5/5
*/
-- --------------------------------------------------------------------------------------
-- Mysql 查询示
-- @author Zhang Peng
-- @date 2018/5/5
-- ----------------------------------------------------------------------------------------
-- -------------------------------------------
-- 查询数据
@ -24,7 +24,7 @@ FROM products;
SELECT DISTINCT vend_id
FROM products;
-- 限制结果
-- 限制查询数量
-- 返回前 5 行1
SELECT *
FROM products

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@ -0,0 +1,119 @@
-- --------------------------------------------------------------------------------------
-- 函数操作影响索引效率示例
-- @author Zhang Peng
-- ----------------------------------------------------------------------------------------
-- 步骤 1、建表
CREATE TABLE tradelog (
id INT(11) UNSIGNED NOT NULL AUTO_INCREMENT COMMENT 'Id',
tradeid VARCHAR(32) DEFAULT NULL,
operator INT(11) DEFAULT NULL,
t_modified DATETIME DEFAULT NULL,
PRIMARY KEY (id),
KEY tradeid(tradeid),
KEY t_modified(t_modified)
)
ENGINE = InnoDB
DEFAULT CHARSET = utf8mb4;
CREATE TABLE trade_detail (
id INT(11) NOT NULL,
tradeid VARCHAR(32) DEFAULT NULL,
trade_step INT(11) DEFAULT NULL, /* 操作步骤 */
step_info VARCHAR(32) DEFAULT NULL, /* 步骤信息 */
PRIMARY KEY (id),
KEY tradeid(tradeid)
)
ENGINE = InnoDB
DEFAULT CHARSET = utf8;
-- 步骤 2、存储过程初始化数据
INSERT INTO trade_detail
VALUES (1, 'aaaaaaaa', 1, 'add');
INSERT INTO trade_detail
VALUES (2, 'aaaaaaaa', 2, 'update');
INSERT INTO trade_detail
VALUES (3, 'aaaaaaaa', 3, 'commit');
INSERT INTO trade_detail
VALUES (4, 'aaaaaaab', 1, 'add');
INSERT INTO trade_detail
VALUES (5, 'aaaaaaab', 2, 'update');
INSERT INTO trade_detail
VALUES (6, 'aaaaaaab', 3, 'update again');
INSERT INTO trade_detail
VALUES (7, 'aaaaaaab', 4, 'commit');
INSERT INTO trade_detail
VALUES (8, 'aaaaaaac', 1, 'add');
INSERT INTO trade_detail
VALUES (9, 'aaaaaaac', 2, 'update');
INSERT INTO trade_detail
VALUES (10, 'aaaaaaac', 3, 'update again');
INSERT INTO trade_detail
VALUES (11, 'aaaaaaac', 4, 'commit');
INSERT INTO tradelog
VALUES (1, 'aaaaaaaa', 1000, now());
INSERT INTO tradelog
VALUES (2, 'aaaaaaab', 1000, now());
INSERT INTO tradelog
VALUES (3, 'aaaaaaac', 1000, now());
DELIMITER ;;
DROP PROCEDURE IF EXISTS init;
CREATE PROCEDURE init()
BEGIN
DECLARE i INT;
SET i = 3;
WHILE i < 10000
DO
INSERT INTO tradelog(tradeid, operator, t_modified)
VALUES (concat(char(97 + (i DIV 1000)), char(97 + (i % 1000 DIV 100)), char(97 + (i % 100 DIV 10)),
char(97 + (i % 10))), i, now());
SET i = i + 1;
END WHILE;
END;;
DELIMITER ;
CALL init();
-- 步骤 3、执行计划查看SQL效率
-- 3.1.1 此 SQL 对索引字段做函数操作,优化器会放弃走树搜索功能,改为全表扫描
EXPLAIN
SELECT count(*)
FROM tradelog
WHERE month(t_modified) = 7;
-- 3.1.2 SQL 优化
EXPLAIN
SELECT count(*)
FROM tradelog
WHERE (t_modified >= '2016-7-1' AND t_modified < '2016-8-1') OR
(t_modified >= '2017-7-1' AND t_modified < '2017-8-1') OR
(t_modified >= '2018-7-1' AND t_modified < '2018-8-1');
-- 3.2.1 此 SQL 对索引字段隐式的使用了转换函数操作,优化器会放弃走树搜索功能,改为全表扫描
-- 相当于 select * from tradelog where CAST(tradid AS signed int) = 110717;
EXPLAIN
SELECT *
FROM tradelog
WHERE tradeid = 110717;
-- 3.3.1 下面两条 SQL 的扫描行数不同
-- 原因是:字符集 utf8mb4 是 utf8 的超集,所以当这两个类型的字符串在做比较的时候,
-- MySQL 内部的操作是,先把 utf8 字符串转成 utf8mb4 字符集,再做比较。
# 需要做字符编码转换
EXPLAIN
SELECT d.*
FROM tradelog l, trade_detail d
WHERE d.tradeid = l.tradeid AND l.id = 2;
# 上面的 SQL 等价于这条注掉的 SQL
# SELECT *
# FROM trade_detail
# WHERE CONVERT(traideid USING utf8mb4) = $l2.tradeid.value;
# 不需要做字符编码转换
EXPLAIN
SELECT l.operator
FROM tradelog l, trade_detail d
WHERE d.tradeid = l.tradeid AND d.id = 2;

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@ -0,0 +1,27 @@
-- --------------------------------------------------------------------------------------
-- 函数操作影响索引效率示例
-- @author Zhang Peng
-- ----------------------------------------------------------------------------------------
CREATE TABLE t (
id INT(11) NOT NULL AUTO_INCREMENT COMMENT 'Id',
c INT(11) DEFAULT NULL,
PRIMARY KEY (id)
)
ENGINE = InnoDB;
DELIMITER ;;
DROP PROCEDURE IF EXISTS init;
CREATE PROCEDURE init()
BEGIN
DECLARE i INT;
SET i = 1;
WHILE(i <= 100000)
DO
INSERT INTO t VALUES (i, i);
SET i = i + 1;
END WHILE;
END;;
DELIMITER ;
CALL init();

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@ -7,7 +7,7 @@
-- --------------------------------------------------------------------- 数据库定义
-- 撤销数据库 test
-- 删除数据库 db_tutorial
DROP DATABASE IF EXISTS db_tutorial;
-- 创建数据库 db_tutorial
@ -18,11 +18,11 @@ USE db_tutorial;
-- --------------------------------------------------------------------- 数据表定义
-- 撤销表 user
-- 删除数据表 user
DROP TABLE IF EXISTS user;
DROP TABLE IF EXISTS vip_user;
-- 创建表 user
-- 创建数据表 user
CREATE TABLE user (
id INT(10) UNSIGNED NOT NULL COMMENT 'Id',
username VARCHAR(64) NOT NULL DEFAULT 'default' COMMENT '用户名',
@ -37,31 +37,32 @@ FROM user;
-- 添加列 age
ALTER TABLE user
ADD age INT(3);
ADD age INT(3);
-- 修改列 age 的类型为 tinyint
ALTER TABLE user
MODIFY COLUMN age TINYINT;
MODIFY COLUMN age TINYINT;
-- 撤销列 age
-- 删除列 age
ALTER TABLE user
DROP COLUMN age;
DROP COLUMN age;
-- --------------------------------------------------------------------- 索引定义
-- 创建表 user 的索引 user_index
CREATE INDEX user_index
ON user(id);
-- 创建表的索引
CREATE INDEX idx_email
ON user(email);
-- 创建表 user 的唯一索引 user_index2
CREATE UNIQUE INDEX user_index2
ON user(id);
-- 创建表的唯一索引
CREATE UNIQUE INDEX uniq_username
ON user(username);
-- 撤销表 user 的索引
-- 删除表 user 的索引
ALTER TABLE user
DROP INDEX user_index;
DROP INDEX idx_email;
ALTER TABLE user
DROP INDEX user_index2;
DROP INDEX uniq_username;
-- --------------------------------------------------------------------- 视图定义
@ -71,5 +72,5 @@ SELECT id, username
FROM user
WHERE id < 10;
-- 撤销表 user 的视图 top_10_user_view
-- 删除表 user 的视图 top_10_user_view
DROP VIEW top_10_user_view;