指定JPA实体“Group”是否是非法的？ [英] Is it illegitimate to name an JPA entity "Group"?
问题描述
我正在开发一个JEE6应用程序，使用JPA 2.0和Hibernate 3.5.2-Final作为Provider（和MySQL 5.1.41）。我的应用程序服务器是Glassfish V3.0.1。
我已经有了一个有效的CRUD应用程序，包含一些实体和关系。
现在我添加了一个名为Group的（非常简单的）实体。实体类如下所示：
包模型
//进口...
@Entity
public class Group {
@Id @GeneratedValue
private Long id;
@NotNull
私人字符串名称;
// Getters and Setters
}
当然，我还将其添加到persistence.xml中，如< class> model.Group< / class> 。我的persistence.xml删除并重新创建了部署的所有表。
因此，当我部署我的应用程序时，除了表组外，我的所有实体的表都会生成。在休眠日志中，我发现了以下错误（这不会阻止应用程序被部署）
[＃| 2010 -06-30T11：54：29.862 + 0200 |信息| glassfish3.0.1 | org.hibernate.cfg.AnnotationBinder | _ThreadID = 11; _ThreadName = Thread-1; |从注释类绑定实体：model.Group |＃]
[＃| 2010-06-30T11：54：29.862 + 0200 | INFO | glassfish3.0.1 | org.hibernate.cfg.annotations.EntityBinder | _ThreadID = 11; _ThreadName = Thread-1; |绑定实体model.Group on table | Group |＃]
[＃| 2010-06-30T11：54：33.773 + 0200 | SEVERE | glassfish3.0.1 | org.hibernate.tool.hbm2ddl.SchemaExport | _ThreadID = 11; _ThreadName = Thread-1; |不成功：创建表组（id bigint不为空auto_increment，名称varchar（255）不为null，主键（id））|＃]
[＃| 2010-06-30T11：54：33.773 + 0200 | SEVERE | glassfish3.0.1 | org.hibernate.tool.hbm2ddl.SchemaExport | _ThreadID = 11; _ThreadName = Thread-1; |您的SQL语法有错误;检查与您的MySQL服务器版本相对应的手册，以便在第1行|＃]
附近使用'Group（id bigint not null auto_increment，name varchar（255）not null，primary ke' 2010-06-30T11：54：54.883 + 0200 |信息| glassfish3.0.1 | org.hibernate.cfg.AnnotationBinder | _ThreadID = 25; _ThreadName = Thread-1; |从注释类绑定实体：model.Group |＃]
[＃| 2010-06-30T11：54：54.884 + 0200 | INFO | glassfish3.0.1 | org.hibernate.cfg.annotations.EntityBinder | _ThreadID = 25; _ThreadName = Thread-1; |绑定实体模型.Group on table Group |＃]
[＃| 2010-06-30T11：54：58.402 + 0200 | SEVERE | glassfish3.0.1 | org.hibernate.tool.hbm2ddl.SchemaExport | _ThreadID = 25; _ThreadName = Thread-1 ; | Unsuccessful：create table Group（id bigint not null auto_increment，name varchar（255）not null，primary key（id））|＃]
[＃| 2010-06-30T11：54：58.403 + 0200 | SEVERE | glassfish3.0.1 | org.hibernate.tool.hbm2ddl.SchemaExport | _ThreadID = 25; _ThreadName = Thread-1; |您的SQL语法有错误;请查看手册对应于您的MySQL服务器版本，在第1行|＃]
附近使用正确的语法以使用'Group（id bigint not null auto_increment，name varchar（255）not null，primary ke' 现在，当我将实体重命名为MyGroup（属性保持不变）时，请相应地更改persistence.xml，然后重新部署我的应用程序，表MyGroup已成功创建！我在日志中发现以下几行显示MyGroup已正确创建：
[＃| 2010-06-30T11：58： 51.456 + 0200 |信息| glassfish3.0.1 | org.hibernate.cfg.AnnotationBinder | _ThreadID = 11; _ThreadName = Thread-1; |从注释类绑定实体：model.MyGroup |＃]
[＃| 2010- 06-30T11：58：51.456 + 0200 |信息| glassfish3.0.1 | org.hibernate.cfg.annotations.EntityBinder | _ThreadID = 11; _ThreadName = Thread-1; |绑定实体model.MyGroup on table MyGroup |＃]
[＃| 2010-06-30T11：59：21.569 + 0200 | INFO | glassfish3.0.1 | org.hibernate.cfg.AnnotationBinder | _ThreadID = 25; _ThreadName = Thread-1; |来自注释类：model的绑定实体。 MyGroup |＃]
[＃| 2010-06-30T11：59：21.569 + 0200 | INFO | glassfish3.0.1 | org.hibernate.cfg.annotations.EntityBinder | _ThreadID = 25; _ThreadName = Thread-1;绑定实体model.MyGroup在表MyGroup |＃]
任何人都知道问题是什么？
好的，我可以将Group重命名为MyGroup，但我真的很想知道这里发生了什么。我现在有什么限制，比如不要调用实体组吗？但是，如果是这样，为什么错误我得到如此不清楚？解决方案
组是数据库中的保留字MySQL查看此处
编辑：
包装模型
//进口...
@Entity
@Table（name =group_table）
public class Group {
@Id @GeneratedValue
private Long id;
@NotNull
私人字符串名称;
// Getters and Setters
}
I'm developing a JEE6-application, using JPA 2.0 and Hibernate 3.5.2-Final as the Provider (and MySQL 5.1.41). My Application Server is Glassfish V3.0.1. I already have a working CRUD-app with some entities and relationships.
Now i added an (really simple) entity with the name "Group". The entity class looks like this:
package model
//Imports...
@Entity
public class Group {
@Id @GeneratedValue
private Long id;
@NotNull
private String name;
//Getters and Setters
}
Of course I also added it to the persistence.xml, like <class>model.Group</class>. My persistence.xml drops and recreates all tables on deploy.
So when i deploy my application, the tables for all my entities are generated, except for the table group. In the hibernate logs, i discovered the following error (which doesn't prevent the application to be deployed)
[#|2010-06-30T11:54:29.862+0200|INFO|glassfish3.0.1|org.hibernate.cfg.AnnotationBinder|_ThreadID=11;_ThreadName=Thread-1;|Binding entity from annotated class: model.Group|#]
[#|2010-06-30T11:54:29.862+0200|INFO|glassfish3.0.1|org.hibernate.cfg.annotations.EntityBinder|_ThreadID=11;_ThreadName=Thread-1;|Bind entity model.Group on table Group|#]
[#|2010-06-30T11:54:33.773+0200|SEVERE|glassfish3.0.1|org.hibernate.tool.hbm2ddl.SchemaExport|_ThreadID=11;_ThreadName=Thread-1;|Unsuccessful: create table Group (id bigint not null auto_increment, name varchar(255) not null, primary key (id))|#]
[#|2010-06-30T11:54:33.773+0200|SEVERE|glassfish3.0.1|org.hibernate.tool.hbm2ddl.SchemaExport|_ThreadID=11;_ThreadName=Thread-1;|You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'Group (id bigint not null auto_increment, name varchar(255) not null, primary ke' at line 1|#]
[#|2010-06-30T11:54:54.883+0200|INFO|glassfish3.0.1|org.hibernate.cfg.AnnotationBinder|_ThreadID=25;_ThreadName=Thread-1;|Binding entity from annotated class: model.Group|#]
[#|2010-06-30T11:54:54.884+0200|INFO|glassfish3.0.1|org.hibernate.cfg.annotations.EntityBinder|_ThreadID=25;_ThreadName=Thread-1;|Bind entity model.Group on table Group|#]
[#|2010-06-30T11:54:58.402+0200|SEVERE|glassfish3.0.1|org.hibernate.tool.hbm2ddl.SchemaExport|_ThreadID=25;_ThreadName=Thread-1;|Unsuccessful: create table Group (id bigint not null auto_increment, name varchar(255) not null, primary key (id))|#]
[#|2010-06-30T11:54:58.403+0200|SEVERE|glassfish3.0.1|org.hibernate.tool.hbm2ddl.SchemaExport|_ThreadID=25;_ThreadName=Thread-1;|You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'Group (id bigint not null auto_increment, name varchar(255) not null, primary ke' at line 1|#]
Now when i rename the entity to something like "MyGroup" (the properties stay the same), alter the persistence.xml accordingly, and redeploy my app, the table "MyGroup" is successfully created! I found the following lines in the logs showing that MyGroup is correctly created:
[#|2010-06-30T11:58:51.456+0200|INFO|glassfish3.0.1|org.hibernate.cfg.AnnotationBinder|_ThreadID=11;_ThreadName=Thread-1;|Binding entity from annotated class: model.MyGroup|#]
[#|2010-06-30T11:58:51.456+0200|INFO|glassfish3.0.1|org.hibernate.cfg.annotations.EntityBinder|_ThreadID=11;_ThreadName=Thread-1;|Bind entity model.MyGroup on table MyGroup|#]
[#|2010-06-30T11:59:21.569+0200|INFO|glassfish3.0.1|org.hibernate.cfg.AnnotationBinder|_ThreadID=25;_ThreadName=Thread-1;|Binding entity from annotated class: model.MyGroup|#]
[#|2010-06-30T11:59:21.569+0200|INFO|glassfish3.0.1|org.hibernate.cfg.annotations.EntityBinder|_ThreadID=25;_ThreadName=Thread-1;|Bind entity model.MyGroup on table MyGroup|#]
Anyone got an idea what the problem is? Okay, i could just rename Group to MyGroup, but i really want to know what's going on here. Is there any restriction i should now of, like "don't call an entity Group"? But if it is so, why is the error i get so unclear?
Group is a reserved word in your database MySQL see here
Edit:
package model
//Imports...
@Entity
@Table(name = "group_table")
public class Group {
@Id @GeneratedValue
private Long id;
@NotNull
private String name;
//Getters and Setters
}
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