我刚开始使用vaadin。我目前使用的是H2数据库，但当我想创建数据库“Upload”时，我收到一个错误：

org.hibernate.tool.schema.spi.CommandAcceptanceException: Error executing DDL "create table upload (id varchar(255) not null, file_name varchar(255) not null, import_date bigint not null, month varchar(255) not null, year varchar(255) not null, primary key (id))" via JDBC Statement
    at org.hibernate.tool.schema.internal.exec.GenerationTargetToDatabase.accept(GenerationTargetToDatabase.java:67) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.tool.schema.internal.SchemaCreatorImpl.applySqlString(SchemaCreatorImpl.java:458) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.tool.schema.internal.SchemaCreatorImpl.applySqlStrings(SchemaCreatorImpl.java:442) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.tool.schema.internal.SchemaCreatorImpl.createFromMetadata(SchemaCreatorImpl.java:325) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.tool.schema.internal.SchemaCreatorImpl.performCreation(SchemaCreatorImpl.java:169) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.tool.schema.internal.SchemaCreatorImpl.doCreation(SchemaCreatorImpl.java:138) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.tool.schema.internal.SchemaCreatorImpl.doCreation(SchemaCreatorImpl.java:124) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.tool.schema.spi.SchemaManagementToolCoordinator.performDatabaseAction(SchemaManagementToolCoordinator.java:168) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.tool.schema.spi.SchemaManagementToolCoordinator.process(SchemaManagementToolCoordinator.java:85) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:335) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:471) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1498) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]

我像教程中一样创建了专用于Upload表的Repository和Service Class。