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[英]Field 'index_id' doesn't have a default value" when trying to use the primary_key as part of composite key in Hibernate
[英]How to change the default value that hibernate inserts for Primary key field?
我有一個名為users的類,其中有一個主鍵userid ...現在,當我將該類的對象放入創建表名為users的表的MYSql數據庫中時,Hibernate放置一個默認行,其主鍵的值為0,其余部分為字段為空...
當我使用@Column(name =“ userid”,Columndefintion =“ int default -1”)時,它仍然會將userid的值設置為0,這是我不想要的。
USER.Java
package schema;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Lob;
import javax.persistence.Table;
@Entity
public class users {
@Id
public int userid;
private String username;
private String pw;
private String fname;
private String lname;
private String gender;
private String dob;
private String jdate;
private String ldate;
private String address;
private String email;
private String tel;
@Column(name="pic")
@Lob
private byte[] pic;
@Column(name="tpic")
@Lob
private byte[] tpic;
public int getUserid() {
return userid;
}
public void setUserid(int userid) {
this.userid = userid;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPw() {
return pw;
}
public void setPw(String pw) {
this.pw = pw;
}
public String getFname() {
return fname;
}
public void setFname(String fname) {
this.fname = fname;
}
public String getLname() {
return lname;
}
public void setLname(String lname) {
this.lname = lname;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public String getDob() {
return dob;
}
public void setDob(String dob) {
this.dob = dob;
}
public String getJdate() {
return jdate;
}
public void setJdate(String jdate) {
this.jdate = jdate;
}
public String getLdate() {
return ldate;
}
public void setLdate(String ldate) {
this.ldate = ldate;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getTel() {
return tel;
}
public void setTel(String tel) {
this.tel = tel;
}
public byte[] getPic() {
return pic;
}
public void setPic(byte[] pic) {
this.pic = pic;
}
public byte[] getTpic() {
return tpic;
}
public void setTpic(byte[] tpic) {
this.tpic = tpic;
}
}
Hibernate.cfg.xml
<?xml version='1.0' encoding='utf-8'?>
<!--
~ Hibernate, Relational Persistence for Idiomatic Java
~
~ Copyright (c) 2010, Red Hat Inc. or third-party contributors as
~ indicated by the @author tags or express copyright attribution
~ statements applied by the authors. All third-party contributions are
~ distributed under license by Red Hat Inc.
~
~ This copyrighted material is made available to anyone wishing to use, modify,
~ copy, or redistribute it subject to the terms and conditions of the GNU
~ Lesser General Public License, as published by the Free Software Foundation.
~
~ This program is distributed in the hope that it will be useful,
~ but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
~ or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
~ for more details.
~
~ You should have received a copy of the GNU Lesser General Public License
~ along with this distribution; if not, write to:
~ Free Software Foundation, Inc.
~ 51 Franklin Street, Fifth Floor
~ Boston, MA 02110-1301 USA
-->
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- Database connection settings -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost:3306/bg</property>
<property name="connection.username">root</property>
<property name="connection.password"/>
<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">1</property>
<!-- Echo all executed SQL to stdout -->
<property name="show_sql">true</property>
<!-- Drop and re-create the database schema on startup -->
<property name="hbm2ddl.auto">update</property>
<mapping class="schema.friendship"/>
<mapping class="schema.users"/>
<mapping class="schema.resources"/>
<mapping class="schema.manipulation"/>
</session-factory>
</hibernate-configuration>
當我嘗試在創建后再次加載數據時,是否有一種方法可以插入不同的默認值coz,當我嘗試插入userid = 0時,它說:原因:java.sql.BatchUpdateException:鍵“ PRIMARY”的條目“ 0”重復'
還使用hbm2ddl.auto作為更新不會更新現有的0,null,null ...列..為什么?
如果要為每行的userid列自動分配一個不同的值,則可以使用@GeneratedValue
批注,例如:
@Id @GeneratedValue(strategy=GenerationType.TABLE)
public int userid;
有關可用的不同生成策略,請參見JPA / Hibernate文檔。
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