请看下面的代码
public String setEmailAccount(String account,String userName, String password) { createConnection(); String result = ""; try { //This part will set the new account con.setAutoCommit(false); PreparedStatement ps = con.prepareStatement("insert into Emails values (?,?,?)"); ps.setString(1,account); ps.setString(2, userName); ps.setString(3, password); int resultInt = ps.executeUpdate(); con.commit(); if(resultInt>0) { result = "Account Created Successfully"; } else { result = "Account creation falied. Error unknown"; } } catch(SQLException sql) { result = sql.getMessage(); sql.printStackTrace(); //If the account exists, then this part will update the current account details if(sql.getMessage().contains("Violation of PRIMARY KEY") || sql.getMessage().contains("SQLIntegrityConstraintViolationException")) { try { con.setAutoCommit(false); PreparedStatement ps = con.prepareStatement("update Emails set userName=?,passwords=? where accountType=?"); ps.setString(1,userName); ps.setString(2, password); ps.setString(3, account); int resultInt = ps.executeUpdate(); con.commit(); if(resultInt>0) { result = "Your "+account+" details has been updated succesfully"; } else { result = "Error updating your "+account+" details. Rollback has not happened"; } } catch(SQLException updateSqlException) { updateSqlException.printStackTrace(); result = "Error updating your " +account+ " details. Everything rollbacked succesfully"; try { con.rollback(); } catch(Exception updateRollbakException) { updateRollbakException.printStackTrace(); result = "Error in updating your " + account + " details. Rollbak failed."; } } catch(Exception updateE) { result = "Error Occured. But your "+account+" data has been updated successfully"; updateE.printStackTrace(); } } else { try { con.rollback(); } catch(Exception ee) { result = "Data insertion failed. RollBack failed. Error is below\n"+ee.getMessage(); } } } catch(Exception e) { e.printStackTrace(); } finally { closeConnection(); } return result; }
这是一个电子邮件配置程序。此方法用于配置电子邮件帐户。用户输入电子邮件帐户类型（yahoo.gmail），密码和用户名。这仅允许将一种电子邮件帐户配置为一种类型的电子邮件帐户（例如：只能存在一个“ yahoo”电子邮件帐户，只能存在一个“ gmail”帐户）
在这里，如果数据已经存在（这意味着已经有一个特定帐户类型的帐户），程序将对其进行更新，而不是直接插入数据。如果没有数据，程序将输入数据。
该程序可与MSSQL Server正常运行。当SQL Server引发Violation of PRIMARY KEY异常时，程序将开始更新当前数据。
Violation of PRIMARY KEY
但是，这不适用于Derby。我正在使用Derby嵌入式版本。我a，当已经有数据并且没有更新任何数据时，出现以下错误。
java.sql.SQLIntegrityConstraintViolationException: The statement was aborted because it would have caused a duplicate key value in a unique or primary key constraint or unique index identified by 'PK_USER' defined on 'EMAILS'. at org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(Unknown Source) at org.apache.derby.impl.jdbc.Util.generateCsSQLException(Unknown Source) at org.apache.derby.impl.jdbc.TransactionResourceImpl.wrapInSQLException(Unknown Source) at org.apache.derby.impl.jdbc.TransactionResourceImpl.handleException(Unknown Source) at org.apache.derby.impl.jdbc.EmbedConnection.handleException(Unknown Source) at org.apache.derby.impl.jdbc.ConnectionChild.handleException(Unknown Source) at org.apache.derby.impl.jdbc.EmbedStatement.executeStatement(Unknown Source) at org.apache.derby.impl.jdbc.EmbedPreparedStatement.executeStatement(Unknown Source) at org.apache.derby.impl.jdbc.EmbedPreparedStatement.executeUpdate(Unknown Source) at email.EmailDBHandler.setEmailAccount(EmailDBHandler.java:59) at email.ConfigureEmail$OKButton.actionPerformed(ConfigureEmail.java:62) at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018) at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341) at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402) at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259) at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252) at java.awt.Component.processMouseEvent(Component.java:6504) at javax.swing.JComponent.processMouseEvent(JComponent.java:3321) at java.awt.Component.processEvent(Component.java:6269) at java.awt.Container.processEvent(Container.java:2229) at java.awt.Component.dispatchEventImpl(Component.java:4860) at java.awt.Container.dispatchEventImpl(Container.java:2287) at java.awt.Component.dispatchEvent(Component.java:4686) at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832) at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492) at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422) at java.awt.Container.dispatchEventImpl(Container.java:2273) at java.awt.Window.dispatchEventImpl(Window.java:2713) at java.awt.Component.dispatchEvent(Component.java:4686) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707) at java.awt.EventQueue.access$000(EventQueue.java:101) at java.awt.EventQueue$3.run(EventQueue.java:666) at java.awt.EventQueue$3.run(EventQueue.java:664) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87) at java.awt.EventQueue$4.run(EventQueue.java:680) at java.awt.EventQueue$4.run(EventQueue.java:678) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) at java.awt.EventQueue.dispatchEvent(EventQueue.java:677) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105) at java.awt.EventDispatchThread.run(EventDispatchThread.java:90) Caused by: java.sql.SQLException: The statement was aborted because it would have caused a duplicate key value in a unique or primary key constraint or unique index identified by 'PK_USER' defined on 'EMAILS'. at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source) at org.apache.derby.impl.jdbc.SQLExceptionFactory40.wrapArgsForTransportAcrossDRDA(Unknown Source) ... 47 more Caused by: ERROR 23505: The statement was aborted because it would have caused a duplicate key value in a unique or primary key constraint or unique index identified by 'PK_USER' defined on 'EMAILS'. at org.apache.derby.iapi.error.StandardException.newException(Unknown Source) at org.apache.derby.impl.sql.execute.IndexChanger.insertAndCheckDups(Unknown Source) at org.apache.derby.impl.sql.execute.IndexChanger.doInsert(Unknown Source) at org.apache.derby.impl.sql.execute.IndexChanger.insert(Unknown Source) at org.apache.derby.impl.sql.execute.IndexSetChanger.insert(Unknown Source) at org.apache.derby.impl.sql.execute.RowChangerImpl.insertRow(Unknown Source) at org.apache.derby.impl.sql.execute.InsertResultSet.normalInsertCore(Unknown Source) at org.apache.derby.impl.sql.execute.InsertResultSet.open(Unknown Source) at org.apache.derby.impl.sql.GenericPreparedStatement.executeStmt(Unknown Source) at org.apache.derby.impl.sql.GenericPreparedStatement.execute(Unknown Source) ... 41 more
以下是SQL表
create table Emails ( accountType varchar(10) constraint pk_user primary key, userName varchar(50) , passwords varchar(50) )
当数据已经存在时，请帮助我更新数据。
您正在使用此语法搜索字符串
if(sql.getMessage().contains("Violation of PRIMARY KEY") || sql.getMessage().contains("SQLIntegrityConstraintViolationException"))
而derby返回此字符串
The statement was aborted because it would have caused a duplicate key value in a unique or primary key constraint or unique index identified by 'PK_USER' defined on 'EMAILS'.
这就是为什么您的if语句不执行的原因
