这是在使用微服务架构时我所碰到的问题，控制台一直报错说我jpa自动建表的表已经存在，但是ddl-auto: update是每次运行程序，没有表格会新建表格，表内有数据不会清空，只会更新

这就是我的错误

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaAutoConfiguration.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.tool.schema.spi.SchemaManagementException: Unable to execute schema management to JDBC target [create table mysql.t_springcloud_student (id integer not null auto_increment, grade varchar(50), name varchar(50), primary key (id))]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1634) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:312) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:308) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1080) ~[spring-context-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:857) ~[spring-context-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543) ~[spring-context-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.13.RELEASE.jar:1.5.13.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693) [spring-boot-1.5.13.RELEASE.jar:1.5.13.RELEASE]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360) [spring-boot-1.5.13.RELEASE.jar:1.5.13.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) [spring-boot-1.5.13.RELEASE.jar:1.5.13.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.13.RELEASE.jar:1.5.13.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.13.RELEASE.jar:1.5.13.RELEASE]
	at com.tanzhixian.microservicestudentprovider1001.MicroserviceStudentProvider1001Application.main(MicroserviceStudentProvider1001Application.java:14) [classes/:na]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_152]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_152]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_152]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_152]
	at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-1.5.13.RELEASE.jar:1.5.13.RELEASE]
Caused by: javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.tool.schema.spi.SchemaManagementException: Unable to execute schema management to JDBC target [create table mysql.t_springcloud_student (id integer not null auto_increment, grade varchar(50), name varchar(50), primary key (id))]
	at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:396) ~[spring-orm-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:371) ~[spring-orm-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:336) ~[spring-orm-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1692) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1630) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	... 21 common frames omitted
Caused by: org.hibernate.tool.schema.spi.SchemaManagementException: Unable to execute schema management to JDBC target [create table mysql.t_springcloud_student (id integer not null auto_increment, grade varchar(50), name varchar(50), primary key (id))]
	at org.hibernate.tool.schema.internal.TargetDatabaseImpl.accept(TargetDatabaseImpl.java:59) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
	at org.hibernate.tool.schema.internal.SchemaMigratorImpl.applySqlString(SchemaMigratorImpl.java:431) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
	at org.hibernate.tool.schema.internal.SchemaMigratorImpl.applySqlStrings(SchemaMigratorImpl.java:420) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
	at org.hibernate.tool.schema.internal.SchemaMigratorImpl.createTable(SchemaMigratorImpl.java:236) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
	at org.hibernate.tool.schema.internal.SchemaMigratorImpl.doMigrationToTargets(SchemaMigratorImpl.java:167) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
	at org.hibernate.tool.schema.internal.SchemaMigratorImpl.doMigration(SchemaMigratorImpl.java:60) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
	at org.hibernate.tool.hbm2ddl.SchemaUpdate.execute(SchemaUpdate.java:134) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
	at org.hibernate.tool.hbm2ddl.SchemaUpdate.execute(SchemaUpdate.java:101) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
	at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:472) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
	at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:444) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
	at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:879) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
	at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:60) ~[spring-orm-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:360) ~[spring-orm-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:384) ~[spring-orm-4.3.17.RELEASE.jar:4.3.17.RELEASE]
	... 25 common frames omitted
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 't_springcloud_student' already exists
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_152]
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_152]
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_152]
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_152]
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:425) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.Util.getInstance(Util.java:408) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:944) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3976) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3912) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2530) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2683) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2482) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.StatementImpl.executeUpdateInternal(StatementImpl.java:1552) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.StatementImpl.executeLargeUpdate(StatementImpl.java:2607) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1480) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.alibaba.druid.filter.FilterChainImpl.statement_executeUpdate(FilterChainImpl.java:2846) ~[druid-1.1.10.jar:1.1.10]
	at com.alibaba.druid.filter.FilterAdapter.statement_executeUpdate(FilterAdapter.java:2508) ~[druid-1.1.10.jar:1.1.10]
	at com.alibaba.druid.filter.FilterEventAdapter.statement_executeUpdate(FilterEventAdapter.java:327) ~[druid-1.1.10.jar:1.1.10]
	at com.alibaba.druid.filter.FilterChainImpl.statement_executeUpdate(FilterChainImpl.java:2844) ~[druid-1.1.10.jar:1.1.10]
	at com.alibaba.druid.proxy.jdbc.StatementProxyImpl.executeUpdate(StatementProxyImpl.java:235) ~[druid-1.1.10.jar:1.1.10]
	at com.alibaba.druid.pool.DruidPooledStatement.executeUpdate(DruidPooledStatement.java:319) ~[druid-1.1.10.jar:1.1.10]
	at org.hibernate.tool.schema.internal.TargetDatabaseImpl.accept(TargetDatabaseImpl.java:56) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
	... 38 common frames omitted

解决方案
其实很简单，我们只需要找到自己在yml文件中jpa所处的位置把它进行注释处理即可，因为我是第一次使用微服务架构，所以不是特别清楚，在网上也没有找到处理方案，所以花费一些时间写这篇博客让新手们解决这个问题