在 Java 中找不到列

Question

我在 Ms-Access 中有一个数据库 table，列名为 CANDIDATE1、CANDIDATE2、CANDIDATE3、CANDIDATE4、CANDIDATE5。我有一个 query 在下面的代码中

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    // TODO add your handling code here:
    try
    {
       String s = (String) jComboBox1.getSelectedItem();
        String sql = "SELECT '"+s+"' FROM results";
        rs = st.executeQuery(sql);
        while(rs.next())
        {
            jLabel1.setText(rs.getString(s));
        }
        JOptionPane.showMessageDialog(null,"U have voted "+jComboBox1.getSelectedItem()+",thank you!");

    }
    catch(Exception e)
    {
        JOptionPane.showMessageDialog(null,e);

    }
}

当我尝试运行程序时，它抛出一个错误 Column not found。我能知道我的代码或查询有什么问题吗？

net.ucanaccess.jdbc.UcanaccessSQLException: Column not found: ADMK
at net.ucanaccess.jdbc.UcanaccessResultSet.getString(UcanaccessResultSet.java:689)  at 

net.ucanaccess.jdbc.UcanaccessResultSet.getString(UcanaccessResultSet.java:689)
    at pack.user_vote.jButton1ActionPerformed(user_vote.java:152)
    at pack.user_vote.access[=12=]0(user_vote.java:21)
    at pack.user_vote.actionPerformed(user_vote.java:87)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2346)
    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:6525)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6290)
    at java.awt.Container.processEvent(Container.java:2234)
    at java.awt.Component.dispatchEventImpl(Component.java:4881)
    at java.awt.Container.dispatchEventImpl(Container.java:2292)
    at java.awt.Component.dispatchEvent(Component.java:4703)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4533)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
    at java.awt.Container.dispatchEventImpl(Container.java:2278)
    at java.awt.Window.dispatchEventImpl(Window.java:2739)
    at java.awt.Component.dispatchEvent(Component.java:4703)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:746)
    at java.awt.EventQueue.access0(EventQueue.java:97)
    at java.awt.EventQueue.run(EventQueue.java:697)
    at java.awt.EventQueue.run(EventQueue.java:691)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.security.ProtectionDomain.doIntersectionPrivilege(ProtectionDomain.java:86)
    at java.awt.EventQueue.run(EventQueue.java:719)
    at java.awt.EventQueue.run(EventQueue.java:717)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:716)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
Caused by: java.sql.SQLException: Column not found: ADMK
    at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
    at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
    at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
    at org.hsqldb.jdbc.JDBCResultSet.findColumn(Unknown Source)
    at org.hsqldb.jdbc.JDBCResultSet.getString(Unknown Source)
    at net.ucanaccess.jdbc.UcanaccessResultSet.getString(UcanaccessResultSet.java:687)
    ... 39 more
Caused by: org.hsqldb.HsqlException: Column not found: ADMK
    at org.hsqldb.error.Error.error(Unknown Source)
    at org.hsqldb.error.Error.error(Unknown Source)
    ... 43 more

注意：我正在使用 ucanaccess 进行数据库连接。

Answer 1

我认为你在添加无用的简单引号，应该是

String sql = "SELECT "+s+" FROM results";

（注意：您正在尝试从列中获取值，而不仅仅是字符串）

在 Java 中找不到列

Column not found in Java

java

sql

database

ucanaccess