【发布时间】：2015-07-15 17:22:57
【问题描述】：
我正在使用 Netbeans IDE 8.02 来操作访问数据库，但是由于删除了驱动程序，我一直在努力使用 UCanAccess。我已经能够将数据插入到数据库中并且能够从数据库中接收数据，但是我正在努力删除一条记录，即使它是一个非常简单的查询。
这是我的方法：
public void VerwyderHemp(String Path, int KledingStukNo){
try {
Class.forName("net.ucanaccess.jdbc.UcanaccessDriver");
conn = DriverManager.getConnection("jdbc:ucanaccess://" + Path);
st = conn.createStatement();
String sql = "DELETE FROM tblHemde WHERE tblHemde.ID = " + KledingStukNo + ";" ;
ResultSet rs = st.executeQuery(sql);
} catch (Exception e) {
e.printStackTrace();
}
}
我在 jFrame 中的 jButton 中使用我的方法，它看起来像这样：
private void jButtonVerwyderHempActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
int KledingstukNo = Integer.parseInt(jTextFieldDeleteHemp.getText());
myHemp.VerwyderHemp(Path2, KledingstukNo);
System.out.println(KledingstukNo);
}
参数“Path2”只是指定数据库的位置并且没有给出任何问题，因为我在类似的方法中使用过它，但我不太确定另一个参数“KledingstukNo”，尽管当我打印出“KledingstukNo”时"，我得到了在"jTextFieldDeleteHemp"中输入的值。
当我连接到我的数据库时，我收到以下消息：
警告：表 tblHemde 元数据中的错误：元数据中表的行数为 8，但 UCanAccess 已找到并加载了 9 条记录。一切都会正常工作，但最好修复您的数据库。
当我尝试删除记录时，我收到以下错误消息：
*
net.ucanaccess.jdbc.UcanaccessSQLException: java.lang.NullPointerException java.lang.NullPointerException
9
at net.ucanaccess.jdbc.UcanaccessStatement.executeQuery(UcanaccessStatement.java:202)
at Klasse.Hemp.VerwyderHemp(Hemp.java:196)
at GUI.FinalGUI.jButtonVerwyderHempActionPerformed(FinalGUI.java:598)
at GUI.FinalGUI.access$600(FinalGUI.java:27)
at GUI.FinalGUI$7.actionPerformed(FinalGUI.java:328)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$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:6516)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6281)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4872)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4698)
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:2719)
at java.awt.Component.dispatchEvent(Component.java:4698)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:747)
at java.awt.EventQueue.access$300(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:706)
at java.awt.EventQueue$3.run(EventQueue.java:704)
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:720)
at java.awt.EventQueue$4.run(EventQueue.java:718)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:717)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
Caused by: java.sql.SQLException: java.lang.NullPointerException java.lang.NullPointerException
at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source)
at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source)
at org.hsqldb.jdbc.JDBCStatement.fetchResult(Unknown Source)
at org.hsqldb.jdbc.JDBCStatement.executeQuery(Unknown Source)
at net.ucanaccess.jdbc.UcanaccessStatement.executeQuery(UcanaccessStatement.java:199)
... 40 more
Caused by: org.hsqldb.HsqlException: java.lang.NullPointerException
at org.hsqldb.error.Error.error(Unknown Source)
at org.hsqldb.result.Result.newErrorResult(Unknown Source)
at org.hsqldb.StatementDMQL.execute(Unknown Source)
at org.hsqldb.Session.executeCompiledStatement(Unknown Source)
at org.hsqldb.Session.executeDirectStatement(Unknown Source)
at org.hsqldb.Session.execute(Unknown Source)
... 43 more
Caused by: java.lang.NullPointerException
at net.ucanaccess.jdbc.UcanaccessConnection.getCtxConnection(UcanaccessConnection.java:87)
at net.ucanaccess.triggers.TriggerDelete.fire(TriggerDelete.java:33)
at org.hsqldb.TriggerDef.pushPair(Unknown Source)
at org.hsqldb.Table.fireTriggers(Unknown Source)
at org.hsqldb.StatementDML.delete(Unknown Source)
at org.hsqldb.StatementDML.executeDeleteStatement(Unknown Source)
at org.hsqldb.StatementDML.getResult(Unknown Source)
... 47 more
BUILD SUCCESSFUL (total time: 24 seconds)*
我没有看到这个错误的原因，请帮忙！
【问题讨论】：
标签： java sql sql-delete ucanaccess