连接SQL常见问题
HTTP Status 500 – Internal Server Error
Type Exception Report
Message Request processing failed; nested exception is org.apache.ibatis.exceptions.PersistenceException:
Description The server encountered an unexpected condition that prevented it from fulfilling the request.
Exception
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.apache.ibatis.exceptions.PersistenceException:
### Error querying database. Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLException: Cannot create PoolableConnectionFactory (Unknown initial character set index '255' received from server. Initial client character set can be forced via the 'characterEncoding' property.)
### The error may exist in file [D:\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\HomeAddrseBooks\WEB-INF\classes\com\zg\dao\HomeAddrseMapper.xml]
### The error may involve homeInfosService.selAllHomeInfos
### The error occurred while executing a query
### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLException: Cannot create PoolableConnectionFactory (Unknown initial character set index '255' received from server. Initial client character set can be forced via the 'characterEncoding' property.)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866)
javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
Root Cause
org.apache.ibatis.exceptions.PersistenceException:
### Error querying database. Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLException: Cannot create PoolableConnectionFactory (Unknown initial character set index '255' received from server. Initial client character set can be forced via the 'characterEncoding' property.)
### The error may exist in file [D:\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\HomeAddrseBooks\WEB-INF\classes\com\zg\dao\HomeAddrseMapper.xml]
### The error may involve homeInfosService.selAllHomeInfos
### The error occurred while executing a query
### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLException: Cannot create PoolableConnectionFactory (Unknown initial character set index '255' received from server. Initial client character set can be forced via the 'characterEncoding' property.)
org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:150)
org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141)
org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:136)
com.zg.dao.impl.HomeAddrseDaoImpl.selAllHomeInfos(HomeAddrseDaoImpl.java:26)
com.zg.service.impl.HomeAddrseService.selAllHomeInfos(HomeAddrseService.java:21)
com.zg.controllers.impl.HomeAddrseController.initPage(HomeAddrseController.java:33)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:498)
org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209)
org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:877)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:783)
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866)
javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
Root Cause
org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLException: Cannot create PoolableConnectionFactory (Unknown initial character set index '255' received from server. Initial client character set can be forced via the 'characterEncoding' property.)
org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:81)
org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:82)
org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:68)
org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:338)
org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:84)
org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:62)
org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:326)
org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156)
org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109)
org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:83)
org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:148)
org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141)
org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:136)
com.zg.dao.impl.HomeAddrseDaoImpl.selAllHomeInfos(HomeAddrseDaoImpl.java:26)
com.zg.service.impl.HomeAddrseService.selAllHomeInfos(HomeAddrseService.java:21)
com.zg.controllers.impl.HomeAddrseController.initPage(HomeAddrseController.java:33)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:498)
org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209)
org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:877)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:783)
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866)
javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
Root Cause
java.sql.SQLException: Cannot create PoolableConnectionFactory (Unknown initial character set index '255' received from server. Initial client character set can be forced via the 'characterEncoding' property.)
org.apache.commons.dbcp2.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:2327)
org.apache.commons.dbcp2.BasicDataSource.createDataSource(BasicDataSource.java:2056)
org.apache.commons.dbcp2.BasicDataSource.getConnection(BasicDataSource.java:1533)
org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:151)
org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:115)
org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:78)
org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:82)
org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:68)
org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:338)
org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:84)
org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:62)
org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:326)
org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156)
org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109)
org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:83)
org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:148)
org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141)
org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:136)
com.zg.dao.impl.HomeAddrseDaoImpl.selAllHomeInfos(HomeAddrseDaoImpl.java:26)
com.zg.service.impl.HomeAddrseService.selAllHomeInfos(HomeAddrseService.java:21)
com.zg.controllers.impl.HomeAddrseController.initPage(HomeAddrseController.java:33)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:498)
org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209)
org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:877)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:783)
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866)
javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
Root Cause
java.sql.SQLException: Unknown initial character set index '255' received from server. Initial client character set can be forced via the 'characterEncoding' property.
com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1055)
com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956)
com.mysql.jdbc.SQLError.createSQLException(SQLError.java:926)
com.mysql.jdbc.ConnectionImpl.configureClientCharacterSet(ConnectionImpl.java:1689)
com.mysql.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:3444)
com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2062)
com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:723)
com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
java.lang.reflect.Constructor.newInstance(Constructor.java:423)
com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)
com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:282)
org.apache.commons.dbcp2.DriverConnectionFactory.createConnection(DriverConnectionFactory.java:38)
org.apache.commons.dbcp2.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:260)
org.apache.commons.dbcp2.BasicDataSource.validateConnectionFactory(BasicDataSource.java:2337)
org.apache.commons.dbcp2.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:2323)
org.apache.commons.dbcp2.BasicDataSource.createDataSource(BasicDataSource.java:2056)
org.apache.commons.dbcp2.BasicDataSource.getConnection(BasicDataSource.java:1533)
org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:151)
org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:115)
org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:78)
org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:82)
org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:68)
org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:338)
org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:84)
org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:62)
org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:326)
org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156)
org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109)
org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:83)
org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:148)
org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141)
org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:136)
com.zg.dao.impl.HomeAddrseDaoImpl.selAllHomeInfos(HomeAddrseDaoImpl.java:26)
com.zg.service.impl.HomeAddrseService.selAllHomeInfos(HomeAddrseService.java:21)
com.zg.controllers.impl.HomeAddrseController.initPage(HomeAddrseController.java:33)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:498)
org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209)
org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:877)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:783)
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866)
javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
Note The full stack trace of the root cause is available in the server logs.
Apache Tomcat/9.0.8
报错原因：1.数据库编码，程序编码，程序编码不一致 2.编码类型无法识别
通过查询可知数据库编码为utf8mb4.
而服务器的编码和程序的编码为utf8.
解决方法：替换了数据库驱动jar包mysql-connector-java-6.0.6.jar
然后报如下问题：
Unknown system variable 'query_cache_size'
问题原因：mysql使用了最新的8.0版本 数据库驱动版本不匹配
解决方法：替换了数据库驱动jar包mysql-connector-java-8.0.11.jar 该JAR包依赖protobuf-java-3.5.1.jar 因此也要加上
连接SQL常见问题
useSSL
后台警告信息
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.
网上很多地方提示加上 useSSL=false 就可以了， 但是如果只是加上这个的话， 会报错如下：
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet successfully received from the server was 250 milliseconds ago. The last packet sent successfully to the server was 242 milliseconds ago.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_101]
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_101]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_101]
at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_101]
xxx
Caused by: javax.net.ssl.SSLHandshakeException: java.security.cert.CertificateException: java.security.cert.CertPathValidatorException: Path does not chain with any of the trust anchors
at sun.security.ssl.Alerts.getSSLException(Alerts.java:192) ~[na:1.8.0_101]
at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1949) ~[na:1.8.0_101]
at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:302) ~[na:1.8.0_101]
at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:296) ~[na:1.8.0_101]
at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1509) ~[na:1.8.0_101]
at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:216) ~[na:1.8.0_101]
at sun.security.ssl.Handshaker.processLoop(Handshaker.java:979) ~[na:1.8.0_101]
at sun.security.ssl.Handshaker.process_record(Handshaker.java:914) ~[na:1.8.0_101]
at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1062) ~[na:1.8.0_101]
at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1375) ~[na:1.8.0_101]
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1403) ~[na:1.8.0_101]
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1387) ~[na:1.8.0_101]
at com.mysql.jdbc.ExportControlled.transformSocketToSSLSocket(ExportControlled.java:186) ~[mysql-connector-java-5.1.46.jar:5.1.46]
... 105 common frames omitted
Caused by: java.security.cert.CertificateException: java.security.cert.CertPathValidatorException: Path does not chain with any of the trust anchors
at com.mysql.jdbc.ExportControlled$X509TrustManagerWrapper.checkServerTrusted(ExportControlled.java:302) ~[mysql-connector-java-5.1.46.jar:5.1.46]
at sun.security.ssl.AbstractTrustManagerWrapper.checkServerTrusted(SSLContextImpl.java:922) ~[na:1.8.0_101]
at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1491) ~[na:1.8.0_101]
... 113 common frames omitted
Caused by: java.security.cert.CertPathValidatorException: Path does not chain with any of the trust anchors
at sun.security.provider.certpath.PKIXCertPathValidator.validate(PKIXCertPathValidator.java:153) ~[na:1.8.0_101]
at sun.security.provider.certpath.PKIXCertPathValidator.engineValidate(PKIXCertPathValidator.java:79) ~[na:1.8.0_101]
at java.security.cert.CertPathValidator.validate(CertPathValidator.java:292) ~[na:1.8.0_101]
at com.mysql.jdbc.ExportControlled$X509TrustManagerWrapper.checkServerTrusted(ExportControlled.java:295) ~[mysql-connector-java-5.1.46.jar:5.1.46]
... 115 common frames omitted
解决方法如下：
在 url 后面加上 autoReconnect=true&useSSL=false
url: jdbc:mysql://10.132.241.120:3306/vue?characterEncoding=utf8&autoReconnect=true&useSSL=false
Unknown system variable 'query_cache_size'
后台报错信息如下：
java.sql.SQLException: Unknown system variable 'query_cache_size'
这个错是 数据库驱动版本和 数据库不一致导致的。解决方法如下：
根据自己的数据库版本去这个地址选择合适的驱动版本
https://mvnrepository.com/artifact/mysql/mysql-connector-java
比如我的数据库版本是 8.0.11，那么对应的驱动为:
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.11</version>
</dependency>
timeZone乱码
报错信息
java.sql.SQLException: The server time zone value 'Öйú±ê׼ʱ¼ä' 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.
这个错是因为 库的时间与系统时间不符导致的。解决方法如下：
在url 后面加上 serverTimezone=GMT
url: jdbc:mysql://localhost:3306/admin?characterEncoding=utf-8&autoReconnect=true&useSSL=false&serverTimezone=GMT
'hibernate.dialect' not set
在Spring Boot下使用JPA报错：'hibernate.dialect' not set，报错信息如下：
Caused by: org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set
at org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.determineDialect(DialectFactoryImpl.java:104)
at org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.buildDialect(DialectFactoryImpl.java:71)
at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:205)
at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:111)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:234)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:206)
at org.hibernate.cfg.Configuration.buildTypeRegistrations(Configuration.java:1885)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1843)
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl$4.perform(EntityManagerFactoryBuilderImpl.java:850)
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl$4.perform(EntityManagerFactoryBuilderImpl.java:843)
at org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl.withTccl(ClassLoaderServiceImpl.java:398)
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:842)
at org.hibernate.jpa.HibernatePersistenceProvider.createContainerEntityManagerFactory(HibernatePersistenceProvider.java:152)
at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:336)
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:318)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1613)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1550)
... 21 more
解决方法：
在 application.yaml 文件中添加以下内容
jpa:
database-platform: org.hibernate.dialect.MySQL5Dialect
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