title: Unique index or primary key violation
body: <p>In my entity below I am using Spring Data JPA with Hibernate and H2 as the database.</p>
  
  <pre><code>package com.java.webservice.entity;
  
  import java.io.Serializable;
  import javax.persistence.*;
  
  
  /**
   * The persistent class for the TABLE1 database table.
   *
   */
  @Entity
  @NamedQuery(name="Table1.findAll", query="SELECT t FROM Table1 t")
  public class Table1 implements Serializable {
      private static final long serialVersionUID = 1L;
  
      @Id
      @GeneratedValue(strategy=GenerationType.AUTO)
      private long id;
  
      @Column(name="INPUT_STRING")
      private String inputString;
  
      @Column(name="REVERSED_STRING")
      private String reversedString;
  
      public Table1() {
      }
  
      public long getId() {
          return this.id;
      }
  
      public void setId(long id) {
          this.id = id;
      }
  
      public String getInputString() {
          return this.inputString;
      }
  
      public void setInputString(String inputString) {
          this.inputString = inputString;
      }
  
      public String getReversedString() {
          return this.reversedString;
      }
  
      public void setReversedString(String reversedString) {
          this.reversedString = reversedString;
      }
  
  } 
  </code></pre>
  
  <p>But as I tried to test it using JUnit Test, I got an error like this:</p>
  
  <pre class="lang-none prettyprint-override"><code>org.springframework.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement
      at org.springframework.orm.jpa.vendor.HibernateJpaDialect.convertHibernateAccessException(HibernateJpaDialect.java:259)
      at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:225)
      at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:521)
      at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:761)
      at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:730)
      at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:487)
      at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:291)
      at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
      at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
      at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)
      at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
      at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:133)
      at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
      at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
      at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
      at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
      at com.sun.proxy.$Proxy36.save(Unknown Source)
      at com.java.webservice.impl.SpringRestServiceImpl.reversedString(SpringRestServiceImpl.java:21)
      at com.java.webservice.database.SpringRestDatabase.stringReversed(SpringRestDatabase.java:49)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:497)
      at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
      at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
      at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
      at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
      at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
      at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
      at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
      at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
      at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252)
      at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
      at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
      at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
      at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
      at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
      at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
      at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
      at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
      at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
      at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
      at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
      at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
      at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
      at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
      at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
      at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
  Caused by: org.hibernate.exception.ConstraintViolationException: could not execute statement
      at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:112)
      at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:42)
      at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:111)
      at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:97)
      at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:207)
      at org.hibernate.engine.jdbc.batch.internal.NonBatchingBatch.addToBatch(NonBatchingBatch.java:45)
      at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2921)
      at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3421)
      at org.hibernate.action.internal.EntityInsertAction.execute(EntityInsertAction.java:89)
      at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:560)
      at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:434)
      at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:337)
      at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:39)
      at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1295)
      at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:468)
      at org.hibernate.internal.SessionImpl.flushBeforeTransactionCompletion(SessionImpl.java:3135)
      at org.hibernate.internal.SessionImpl.beforeTransactionCompletion(SessionImpl.java:2352)
      at org.hibernate.engine.jdbc.internal.JdbcCoordinatorImpl.beforeTransactionCompletion(JdbcCoordinatorImpl.java:485)
      at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.beforeCompletionCallback(JdbcResourceLocalTransactionCoordinatorImpl.java:147)
      at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.access$100(JdbcResourceLocalTransactionCoordinatorImpl.java:38)
      at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.commit(JdbcResourceLocalTransactionCoordinatorImpl.java:231)
      at org.hibernate.engine.transaction.internal.TransactionImpl.commit(TransactionImpl.java:65)
      at org.hibernate.jpa.internal.TransactionImpl.commit(TransactionImpl.java:61)
      at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:517)
      ... 45 more
  Caused by: org.h2.jdbc.JdbcSQLException: Unique index or primary key violation: "PRIMARY_KEY_9 ON PUBLIC.TABLE1(ID) VALUES (1, 3)"; SQL statement:
  insert into Table1 (INPUT_STRING, REVERSED_STRING, id) values (?, ?, ?) [23505-193]
      at org.h2.message.DbException.getJdbcSQLException(DbException.java:345)
      at org.h2.message.DbException.get(DbException.java:179)
      at org.h2.message.DbException.get(DbException.java:155)
      at org.h2.index.BaseIndex.getDuplicateKeyException(BaseIndex.java:103)
      at org.h2.mvstore.db.MVSecondaryIndex.checkUnique(MVSecondaryIndex.java:231)
      at org.h2.mvstore.db.MVSecondaryIndex.add(MVSecondaryIndex.java:190)
      at org.h2.mvstore.db.MVTable.addRow(MVTable.java:704)
      at org.h2.command.dml.Insert.insertRows(Insert.java:156)
      at org.h2.command.dml.Insert.update(Insert.java:114)
      at org.h2.command.CommandContainer.update(CommandContainer.java:98)
      at org.h2.command.Command.executeUpdate(Command.java:258)
      at org.h2.jdbc.JdbcPreparedStatement.executeUpdateInternal(JdbcPreparedStatement.java:160)
      at org.h2.jdbc.JdbcPreparedStatement.executeUpdate(JdbcPreparedStatement.java:146)
      at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:204)
      ... 64 more
  </code></pre>
  
  <p>Below is also my code for DB Unit Testing:</p>
  
  <pre><code>package com.java.webservice.database;
  
  import static org.junit.Assert.assertTrue;
  
  import java.util.List;
  
  import org.junit.Test;
  import org.junit.runner.RunWith;
  import org.springframework.beans.factory.annotation.Autowired;
  import org.springframework.test.context.ContextConfiguration;
  import org.springframework.test.context.TestExecutionListeners;
  import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
  import org.springframework.test.context.support.DependencyInjectionTestExecutionListener;
  import org.springframework.test.context.support.DirtiesContextTestExecutionListener;
  
  import com.github.springtestdbunit.DbUnitTestExecutionListener;
  import com.github.springtestdbunit.TransactionDbUnitTestExecutionListener;
  import com.github.springtestdbunit.annotation.DatabaseSetup;
  import com.java.webservice.dao.SpringRestDAO;
  import com.java.webservice.entity.Table1;
  import com.java.webservice.service.SpringRestService;
  
  
  @TestExecutionListeners({
      DependencyInjectionTestExecutionListener.class,
      DirtiesContextTestExecutionListener.class,
      TransactionDbUnitTestExecutionListener.class,
      DbUnitTestExecutionListener.class
  })
  @RunWith(SpringJUnit4ClassRunner.class)
  @ContextConfiguration("classpath:spring/application-test.xml")
  @DatabaseSetup("classpath:spring/data.xml")
  public class SpringRestDatabase {
  
      @Autowired
      private SpringRestService service;
  
      @Autowired
      private SpringRestDAO dao;
  
      @Test
      public void findAll(){
          List&lt;Table1&gt; list = (List&lt;Table1&gt;) dao.findAll();
          assertTrue("tupni".equals(list.get(0).getReversedString()));
      }
  
      @Test
      public void stringReversed(){
          assertTrue("tupni".equals(service.reversedString("input")));
      }
  
      @Test
      public void inputString(){
          service.inputString("INPUT", "TUPNI");
      }
  
  
  }
  </code></pre>
  
  <p>Below is SpringRestServiceImpl.java</p>
  
  <pre><code>package com.java.webservice.impl;
  import org.springframework.beans.factory.annotation.Autowired;
  import org.springframework.stereotype.Component;
  import org.springframework.stereotype.Service;
  
  import com.java.webservice.dao.SpringRestDAO;
  import com.java.webservice.entity.Table1;
  import com.java.webservice.service.SpringRestService;
  
  
  @Service
  public class SpringRestServiceImpl implements SpringRestService{
      @Autowired
      SpringRestDAO dao; 
      public String reversedString(String string) {
          String result = new StringBuilder(string).reverse().toString();
          Table1 entity = new Table1();
          entity.setInputString(string);
          entity.setReversedString(result);
          dao.save(entity);
          return result;
      }
      public Table1 inputString(String inputString, String reversedString) {
  
          return null;
      }
  }
  </code></pre>
  
  <p>Can somebody help me how to debug this kind of code? Thanks a lot.</p>