【MySQL】MySQL相关问题记录

【1】IDEA连接MySQL报错

问题：Server returns invalid timezone. Go to 'Advanced' tab and set ‘serverTimezone’ property manually

解决：

• Windows：服务 -> 查看mysql服务属性 -> 在my.ini中添加：default-time_zone='+08:00' -> 重启mysql
• Linux：whereis my.cnf -> vim my.cnf -> 在my.cnf中添加：default-time_zone='+08:00' -> 重启mysql

【2】MySQL安装

MySQL的配置文件默认存放在/etc/my.cnf或者/etc/mysql/my.cnf

[client]
default-character-set = utf8

[mysqld]
default-storage-engine = INNODB
character-set-server = utf8mb4
collation-server = utf8mb4_general_ci

重启MySQL后，可以通过MySQL的客户端命令行检查编码：

show variables like '%char%';

Maven依赖

注意到这里添加依赖的scope是runtime，因为编译Java程序并不需要MySQL的这个jar包，只有在运行期才需要使用。如果把runtime改成compile，虽然也能正常编译，但是在IDE里写程序的时候，会多出来一大堆类似com.mysql.jdbc.Connection这样的类，非常容易与Java标准库的JDBC接口混淆，所以坚决不要设置为compile

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.47</version>
    <scope>runtime</scope>
</dependency>

新建数据库并插入数据进行操作

-- 创建数据库learjdbc:
DROP DATABASE IF EXISTS learnjdbc;
CREATE DATABASE learnjdbc;

-- 创建登录用户learn/口令learnpassword
CREATE USER IF NOT EXISTS learn@'%' IDENTIFIED BY 'learnpassword';
GRANT ALL PRIVILEGES ON learnjdbc.* TO learn@'%' WITH GRANT OPTION;
FLUSH PRIVILEGES;

-- 创建表students:
USE learnjdbc;
CREATE TABLE students (
  id BIGINT AUTO_INCREMENT NOT NULL,
  name VARCHAR(50) NOT NULL,
  gender TINYINT(1) NOT NULL,
  grade INT NOT NULL,
  score INT NOT NULL,
  PRIMARY KEY(id)
) Engine=INNODB DEFAULT CHARSET=UTF8;

-- 插入初始数据:
INSERT INTO students (name, gender, grade, score) VALUES ('小明', 1, 1, 88);
INSERT INTO students (name, gender, grade, score) VALUES ('小红', 1, 1, 95);
INSERT INTO students (name, gender, grade, score) VALUES ('小军', 0, 1, 93);
INSERT INTO students (name, gender, grade, score) VALUES ('小白', 0, 1, 100);
INSERT INTO students (name, gender, grade, score) VALUES ('小牛', 1, 2, 96);
INSERT INTO students (name, gender, grade, score) VALUES ('小兵', 1, 2, 99);
INSERT INTO students (name, gender, grade, score) VALUES ('小强', 0, 2, 86);
INSERT INTO students (name, gender, grade, score) VALUES ('小乔', 0, 2, 79);
INSERT INTO students (name, gender, grade, score) VALUES ('小青', 1, 3, 85);
INSERT INTO students (name, gender, grade, score) VALUES ('小王', 1, 3, 90);
INSERT INTO students (name, gender, grade, score) VALUES ('小林', 0, 3, 91);
INSERT INTO students (name, gender, grade, score) VALUES ('小贝', 0, 3, 77);

在控制台输入mysql -u root -p，输入root口令后以root身份，把上述SQL贴到控制台执行一遍就行。如果你运行的是最新版MySQL 8.x，需要调整一下CREATE USER语句