Question

错误是：

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException：你有一个 SQL语法错误;查看与您的手册相对应的手册 MySQL服务器版本，用于在'book_id =附近使用正确的语法 'DSP123''在第1行 at sun.reflect.NativeConstructorAccessorImpl.newInstance0（Native Method） at sun.reflect.NativeConstructorAccessorImpl.newInstance（NativeConstructorAccessorImpl.java:39） at sun.reflect.DelegatingConstructorAccessorImpl.newInstance（DelegatingConstructorAccessorImpl.java:27） at java.lang.reflect.Constructor.newInstance（Constructor.java:513）在com.mysql.jdbc.Util.handleNewInstance（Util.java:411）在com.mysql.jdbc.Util.getInstance（Util.java:386）在com.mysql.jdbc.SQLError.createSQLException（SQLError.java:1052）在com.mysql.jdbc.MysqlIO.checkErrorPacket（MysqlIO.java:3609）在com.mysql.jdbc.MysqlIO.checkErrorPacket（MysqlIO.java:3541）在com.mysql.jdbc.MysqlIO.sendCommand（MysqlIO.java:2002）在com.mysql.jdbc.MysqlIO.sqlQueryDirect（MysqlIO.java:2163）在com.mysql.jdbc.ConnectionImpl.execSQL（ConnectionImpl.java:2624） at com.mysql.jdbc.PreparedStatement.executeInternal（PreparedStatement.java:2127）在com.mysql.jdbc.PreparedStatement.executeUpdate（PreparedStatement.java:2427）在com.mysql.jdbc.PreparedStatement.executeUpdate（PreparedStatement.java:2345）在com.mysql.jdbc.PreparedStatement.executeUpdate（PreparedStatement.java:2330）在Frames.Books.jButton2ActionPerformed（Books.java:424） at Frames.Books.access $ 300（Books.java:26）在Frames.Books $ 4.actionPerformed（Books.java:181）在javax.swing.AbstractButton.fireActionPerformed（AbstractButton.java:1995）在javax.swing.AbstractButton $ Handler.actionPerformed（AbstractButton.java:2318）在javax.swing.DefaultButtonModel.fireActionPerformed（DefaultButtonModel.java:387）在javax.swing.DefaultButtonModel.setPressed（DefaultButtonModel.java:242）在javax.swing.plaf.basic.BasicButtonListener.mouseReleased（BasicButtonListener.java:236） at java.awt.Component.processMouseEvent（Component.java:6263）在javax.swing.JComponent.processMouseEvent（JComponent.java:3267） at java.awt.Component.processEvent（Component.java:6028） at java.awt.Container.processEvent（Container.java:2041） at java.awt.Component.dispatchEventImpl（Component.java:4630） at java.awt.Container.dispatchEventImpl（Container.java:2099） at java.awt.Component.dispatchEvent（Component.java:4460） at java.awt.LightweightDispatcher.retargetMouseEvent（Container.java:4574） at java.awt.LightweightDispatcher.processMouseEvent（Container.java:4238） at java.awt.LightweightDispatcher.dispatchEvent（Container.java:4168） at java.awt.Container.dispatchEventImpl（Container.java:2085） at java.awt.Window.dispatchEventImpl（Window.java:2478） at java.awt.Component.dispatchEvent（Component.java:4460） at java.awt.EventQueue.dispatchEvent（EventQueue.java:599） at java.awt.EventDispatchThread.pumpOneEventForFilters（EventDispatchThread.java:269） at java.awt.EventDispatchThread.pumpEventsForFilter（EventDispatchThread.java:184） at java.awt.EventDispatchThread.pumpEventsForHierarchy（EventDispatchThread.java:174） at java.awt.EventDispatchThread.pumpEvents（EventDispatchThread.java:169） at java.awt.EventDispatchThread.pumpEvents（EventDispatchThread.java:161）在java.awt.EventDispatchThread.run（EventDispatchThread.java:122）

代码是：

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    String bookid = jTextField2.getText();
    String doi = "";
    Calendar cal = new GregorianCalendar();
    doi = doi + cal.get(Calendar.YEAR) + "-" + cal.get(Calendar.MONTH) + "-" + cal.get(Calendar.DAY_OF_MONTH);
    String sql = "insert into library.issue values ('"+ bookid + "','librarian','"+ username + "','" + doi + "')";
    try
    {
        int i = st.executeUpdate(sql);
        if(i>0)
           JOptionPane.showMessageDialog(null,"BOOK IS ISSUED","SUCCESS",JOptionPane.PLAIN_MESSAGE);
        else
           JOptionPane.showMessageDialog(null,"problem in issuing book","FAILURE",JOptionPane.ERROR_MESSAGE);
        bookid = bookid.toUpperCase();
        String sql1 = "update library.books set status = " + 1 + "where book_id = '" + bookid + "'";
        PreparedStatement pstmt=c.prepareStatement(sql1);
        int j= pstmt.executeUpdate() ;
        //int j = st.executeUpdate(sql1);
    }
    catch(Exception ex)
    {
        ex.printStackTrace();
    }
}

Answer 1

在where之前插入一个空格：

String sql1 = "update library.books set status = " + 1 
      + " where book_id = '" + bookid + "'";

Answer 2

检查一次

String sql1 = "update library.books set status =  1 where book_id = '" + bookid + "'";

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException

2 个答案: