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锁定老帖子 主题：为什么我的表被删除了？
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发表时间：2003-09-16
session建立的时候会删除数据库中的表么？（初学不懂）
================程序============= Configuration cfg = new Configuration();.addClass(Bzqj.class);;
SessionFactory sessions = cfg.buildSessionFactory();;
Session s = sessions.openSession();;
Query q = s.createQuery("from Bzqj");;
for (Iterator it = q.iterate();;it.hasNext();; );{
Bzqj b = (Bzqj);it.next();;
System.out.println("##JGBH:"+b.getJGBH(););;
}执行后，数据库中原来的表没了，怎么回事？
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发表时间：2003-09-16
肯定不是Hibernate的问题，Hibernate还不具备向数据库发送DDL语句的功能耶
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发表时间：2003-09-16
test.java
package hibernatedemo;
import hibernatedemo.person;
import java.util.*;
import net.sf.hibernate.Query;
import net.sf.hibernate.Session;
import net.sf.hibernate.SessionFactory;
import net.sf.hibernate.cfg.Configuration;
import net.sf.hibernate.tool.hbm2ddl.SchemaExport;
public class Test {
public static void main(String[] args); throws Exception {
Configuration cfg = new Configuration();.addClass(person.class);;
SessionFactory sessions = cfg.buildSessionFactory();;
new SchemaExport(cfg);.create(true, true);;
Session s = sessions.openSession();;
Query q = s.createQuery("from person");;
for (Iterator it = q.iterate();;it.hasNext();;);{
person b = (person);it.next();;
System.out.println("##name:"+b.getName(););;
}
}
}
person.java package hibernatedemo;
public class person {
private String name;
private String address;
private String id;
public person();{
}
public String getId(); {
return id;
}
public void setId(String id); {
this.id = id;
}
public String getName(); {
return name;
}
public void setName(String name); {
this.name = name;
}
public String getAddress(); {
return address;
}
public void setAddress(String address); {
this.address = address;
}
}
person.hbm.xml <?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
<class name="hibernatedemo.person" >
<id name="id"
column="id"
type="java.lang.String">
<generator
class="assigned"/>
</id>
<property
name="name"
type="java.lang.String"
column="name"/>
<property
name="address"
type="java.lang.String"
column="pass"/>
</class>
</hibernate-mapping>
数据库是mysql，服务器tomcat 执行的时候控制台信息
2003-9-16 10:36:12 net.sf.hibernate.cfg.Environment <clinit>
信息: Hibernate 2.1 beta 3
2003-9-16 10:36:12 net.sf.hibernate.cfg.Environment <clinit>
信息: loaded properties from resource hibernate.properties: {hibernate.connection.driver_class=com.mysql.jdbc.Driver, hibernate.cglib.use_reflection_optimizer=true, hibernate.dialect=net.sf.hibernate.dialect.MySQLDialect, hibernate.jdbc.use_streams_for_binary=true, hibernate.jdbc.batch_size=0, hibernate.query.substitutions=true 1, false 0, yes 'Y', no 'N', hibernate.query.imports=net.sf.hibernate.test, net.sf.hibernate.eg, hibernate.connection.username=root, hibernate.connection.url=jdbc:mysql://localhost/hibernatedb, hibernate.connection.password=, hibernate.statement_cache.size=25, hibernate.connection.pool_size=1}
2003-9-16 10:36:12 net.sf.hibernate.cfg.Environment <clinit>
信息: using java.io streams to persist binary types
2003-9-16 10:36:12 net.sf.hibernate.cfg.Environment <clinit>
信息: using CGLIB reflection optimizer
2003-9-16 10:36:12 net.sf.hibernate.cfg.Configuration addClass
信息: Mapping resource: hibernatedemo/person.hbm.xml
2003-9-16 10:36:15 net.sf.hibernate.cfg.Binder bindRootClass
信息: Mapping class: hibernatedemo.person -> person
2003-9-16 10:36:15 net.sf.hibernate.cfg.Configuration secondPassCompile
信息: processing one-to-many association mappings
2003-9-16 10:36:15 net.sf.hibernate.cfg.Configuration secondPassCompile
信息: processing one-to-one association property references
2003-9-16 10:36:15 net.sf.hibernate.cfg.Configuration secondPassCompile
信息: processing foreign key constraints
2003-9-16 10:36:15 net.sf.hibernate.dialect.Dialect <init>
信息: Using dialect: net.sf.hibernate.dialect.MySQLDialect
2003-9-16 10:36:15 net.sf.hibernate.cfg.SettingsFactory buildSettings
信息: Use outer join fetching: true
2003-9-16 10:36:15 net.sf.hibernate.connection.DriverManagerConnectionProvider configure
信息: Using Hibernate built-in connection pool (not for production use!);
2003-9-16 10:36:15 net.sf.hibernate.connection.DriverManagerConnectionProvider configure
信息: Hibernate connection pool size: 1
2003-9-16 10:36:15 net.sf.hibernate.connection.DriverManagerConnectionProvider configure
信息: using driver: com.mysql.jdbc.Driver at URL: jdbc:mysql://localhost/hibernatedb
2003-9-16 10:36:15 net.sf.hibernate.connection.DriverManagerConnectionProvider configure
信息: connection properties: {user=root, password=}
2003-9-16 10:36:15 net.sf.hibernate.transaction.TransactionManagerLookupFactory getTransactionManagerLookup
信息: No TransactionManagerLookup configured (use of process level read-write cache is not recommended);
2003-9-16 10:36:16 net.sf.hibernate.cfg.SettingsFactory buildSettings
信息: Use scrollable result sets: true
2003-9-16 10:36:16 net.sf.hibernate.cfg.SettingsFactory buildSettings
信息: Query language substitutions: {no='N', true=1, yes='Y', false=0}
2003-9-16 10:36:16 net.sf.hibernate.cfg.SettingsFactory buildSettings
信息: cache provider: net.sf.hibernate.cache.JCSCacheProvider
2003-9-16 10:36:16 net.sf.hibernate.cfg.Configuration configureCaches
信息: instantiating and configuring caches
2003-9-16 10:36:16 net.sf.hibernate.impl.SessionFactoryImpl <init>
信息: building session factory
2003-9-16 10:36:18 net.sf.hibernate.impl.SessionFactoryObjectFactory addInstance
信息: no JNDI name configured
2003-9-16 10:36:18 net.sf.hibernate.dialect.Dialect <init>
信息: Using dialect: net.sf.hibernate.dialect.MySQLDialect
2003-9-16 10:36:18 net.sf.hibernate.cfg.Configuration secondPassCompile
信息: processing one-to-many association mappings
2003-9-16 10:36:18 net.sf.hibernate.cfg.Configuration secondPassCompile
信息: processing one-to-one association property references
2003-9-16 10:36:18 net.sf.hibernate.cfg.Configuration secondPassCompile
信息: processing foreign key constraints
2003-9-16 10:36:18 net.sf.hibernate.cfg.Configuration secondPassCompile
信息: processing one-to-many association mappings
2003-9-16 10:36:18 net.sf.hibernate.cfg.Configuration secondPassCompile
信息: processing one-to-one association property references
2003-9-16 10:36:18 net.sf.hibernate.cfg.Configuration secondPassCompile
信息: processing foreign key constraints
2003-9-16 10:36:18 net.sf.hibernate.tool.hbm2ddl.SchemaExport execute
信息: Running hbm2ddl schema export
2003-9-16 10:36:18 net.sf.hibernate.tool.hbm2ddl.SchemaExport execute
信息: exporting generated schema to database
2003-9-16 10:36:18 net.sf.hibernate.connection.DriverManagerConnectionProvider configure
信息: Using Hibernate built-in connection pool (not for production use!);
2003-9-16 10:36:18 net.sf.hibernate.connection.DriverManagerConnectionProvider configure
信息: Hibernate connection pool size: 1
2003-9-16 10:36:18 net.sf.hibernate.connection.DriverManagerConnectionProvider configure
信息: using driver: com.mysql.jdbc.Driver at URL: jdbc:mysql://localhost/hibernatedb
2003-9-16 10:36:18 net.sf.hibernate.connection.DriverManagerConnectionProvider configure
信息: connection properties: {user=root, password=}
drop table person
create table person (
id VARCHAR(255); not null,
name VARCHAR(255);,
pass VARCHAR(255);,
primary key (id);
);
2003-9-16 10:36:18 net.sf.hibernate.tool.hbm2ddl.SchemaExport execute
信息: schema export complete
2003-9-16 10:36:18 net.sf.hibernate.connection.DriverManagerConnectionProvider close
信息: cleaning up connection pool: jdbc:mysql://localhost/hibernatedb
2003-9-16 10:36:18 net.sf.hibernate.connection.DriverManagerConnectionProvider close
信息: cleaning up connection pool: jdbc:mysql://localhost/hibernatedb
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发表时间：2003-09-16
呵呵，难怪，难怪，原来Hibernate也可以自动建表，枉我还在jdon和别人争，被别人说JDO有自动建表功能，Hibernate没有，原来也是有滴。
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发表时间：2003-09-16
:) HAHA，问题解决，谢谢2位的帮忙。 我郁闷了1天了
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发表时间：2003-09-16
呵呵，其实我早就在用了， 只不过一直糊涂的认为不支持。
SchemaExport dbExport = new SchemaExport(conf);;
dbExport.setOutputFile("db\\testsub.txt");;
dbExport.create(true, true);;
dbExport.create(true, true); 方法中第一个参数是用来决定是否产生DDL,第二个参数是用来决定是否执行DDL |
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发表时间：2003-09-18
关于自动建表我们通常需要这样的功能：
数据库中不存在表的话则创建，如果存在就不要先Drop再创建了。否则数据都丢失了。 这样我们的系统打包后第一次运行就可以建好表，以后就使用这些表而不再创建了。 各位有何好的方法？ |
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发表时间：2003-09-18
你可以先尝试着查询一下，如果捕获的异常说明没有表，就创建之；反之则不创建
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