mysql8.0后产生的错误

mysql连接错误，有时候存在时区问题，
错误提示：
The server time zone value ‘¥x¥_¼Ð·Ç®É¶¡’ is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.

解决办法：
在jdbc连接的url后面加上serverTimezone=Asia/Shanghai,原因是因为 mysql 属于 oralce 公司,oracle 公司位于美国所以时区跟我们不同，我们需要更改为我们国内的时期

jdbc.url=jdbc:mysql://localhost:3306/xxx?useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai

Thu Aug 01 04:57:12 UTC 2019 WARN: Establishing SSL connection without
server’s identity verification is not recommended. According to MySQL
5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn’t set. For compliance
with existing applications not using SSL the verifyServerCertificate
property is set to ‘false’. You need either to explicitly disable SSL
by setting useSSL=false, or set useSSL=true and provide truststore for
server certificate verification.

jdbc.url=jdbc:mysql://localhost:3306/xxx?useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai&useSSL=false

---

java.sql.SQLException: Unknown system variable ‘query_cache_size’

解决办法：

如 mybatis使用 mysql-5.1.14的驱动程序，而mybatis配置的数据源连接的是 mysql-8.0.11 ，修改 pom文件即可，如下：

<dependency>
    <groupId>mysqlgroupId>
    <artifactId>mysql-connector-javaartifactId>
    <version>8.0.11version>
dependency>

根据官方的说法是 :

The query cache is deprecated as of MySQL 5.7.20, and is removed in MySQL 8.0. Deprecation includes query_cache_size.

意思是query cache在MySQL5.7.20就已经过时了，而在MySQL8.0之后就已经被移除了。