java.sql.SQLException：开始之前的结果集...如何删除此错误

我开发员工工资管理使用Java和MySQL .. 我想生成一个PDF的... 但当我点击生成工资单button..then这个错误发生... 我产生滑动按钮的代码是在这里：java.sql.SQLException：开始之前的结果集...如何删除此错误

enter code here 
      private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {           

    String value = txt_firstname.getText(); 
    String value0 = txt_surname.getText(); 
    String value1 = txt_id.getText(); 
    String value2 = txt_desig.getText(); 
    String value3 = txt_dep.getText(); 

     JFileChooser dialog = new JFileChooser(); 
     dialog.setSelectedFile(new File(value +" "+ value0+"-Salary Slip"+".pdf")); 
     int dialogResult = dialog.showSaveDialog(null); 
     if (dialogResult==JFileChooser.APPROVE_OPTION){ 
      String filePath = dialog.getSelectedFile().getPath(); 
      try { 
     // TODO add your handling code here: 


     String sql ="select * from Deductions where emp_id = '"+value1+"'"; 
     pst=conn.prepareStatement(sql); 
     rs=pst.executeQuery(); 
     String val = rs.getString(5); 
     String reason = rs.getString(6); 

     rs.close(); 
     pst.close(); 

     String sq ="select * from Allowance where emp_id = '"+value1+"'"; 
     pst=conn.prepareStatement(sq); 
     rs=pst.executeQuery(); 


     int calcTotal = Integer.parseInt(txt_salary.getText()); 
     float x = Float.valueOf(rs.getString(9)); 
     int v = Integer.parseInt(val); 
     float total = calcTotal +x-v; 

     Document myDocument = new Document(); 
     PdfWriter myWriter = PdfWriter.getInstance(myDocument, new FileOutputStream(filePath)); 
     myDocument.open(); 

     myDocument.add(new Paragraph("PAY SLIP",FontFactory.getFont(FontFactory.TIMES_BOLD,20,Font.BOLD))); 
     myDocument.add(new Paragraph(new Date().toString())); 
     myDocument.add(new Paragraph("-------------------------------------------------------------------------------------------")); 
     myDocument.add((new Paragraph("EMPLOYEE DETAILS",FontFactory.getFont(FontFactory.TIMES_ROMAN,15,Font.BOLD)))); 
     myDocument.add((new Paragraph("Name of Employee: " +value + " "+value0,FontFactory.getFont(FontFactory.TIMES_ROMAN,10,Font.PLAIN)))); 
     myDocument.add((new Paragraph("Designation: "+value2,FontFactory.getFont(FontFactory.TIMES_ROMAN,10,Font.PLAIN)))); 
     myDocument.add((new Paragraph("Department: "+value3,FontFactory.getFont(FontFactory.TIMES_ROMAN,10,Font.PLAIN)))); 
     myDocument.add(new Paragraph("-------------------------------------------------------------------------------------------")); 
     myDocument.add(new Paragraph("SALARY",FontFactory.getFont(FontFactory.TIMES_ROMAN,15,Font.BOLD))); 
     myDocument.add(new Paragraph("Basic Salary: $"+calcTotal,FontFactory.getFont(FontFactory.TIMES_ROMAN,10,Font.PLAIN))); 
     myDocument.add(new Paragraph("Overtime: "+rs.getString(2)+" Hours",FontFactory.getFont(FontFactory.TIMES_ROMAN,10,Font.PLAIN))); 
     myDocument.add(new Paragraph("Medical: $" +rs.getString(3),FontFactory.getFont(FontFactory.TIMES_ROMAN,10,Font.PLAIN))); 
     myDocument.add(new Paragraph("Bonus: $"+rs.getString(4),FontFactory.getFont(FontFactory.TIMES_ROMAN,10,Font.PLAIN))); 
     myDocument.add(new Paragraph("Other: $"+rs.getString(5),FontFactory.getFont(FontFactory.TIMES_ROMAN,10,Font.PLAIN))); 
     myDocument.add(new Paragraph("-------------------------------------------------------------------------------------------")); 
     myDocument.add(new Paragraph("DEDUCTION",FontFactory.getFont(FontFactory.TIMES_ROMAN,15,Font.BOLD))); 
     myDocument.add(new Paragraph("Deduction Details: "+reason,FontFactory.getFont(FontFactory.TIMES_ROMAN,10,Font.PLAIN))); 
     myDocument.add(new Paragraph("Total Deductions : $"+val ,FontFactory.getFont(FontFactory.TIMES_ROMAN,10,Font.PLAIN))); 
     myDocument.add(new Paragraph("-------------------------------------------------------------------------------------------")); 
     myDocument.add(new Paragraph("TOTAL PAYMENT",FontFactory.getFont(FontFactory.TIMES_ROMAN,15,Font.BOLD))); 
     myDocument.add(new Paragraph("Total Earnings: "+rs.getString(9),FontFactory.getFont(FontFactory.TIMES_ROMAN,10,Font.PLAIN))); 
     myDocument.add(new Paragraph("Net Pay : " +total,FontFactory.getFont(FontFactory.TIMES_ROMAN,10,Font.PLAIN))); 
     myDocument.add(new Paragraph("-------------------------------------------------------------------------------------------")); 


     myDocument.newPage(); 
     myDocument.close(); 
     JOptionPane.showMessageDialog(null,"Report was successfully generated"); 

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


} 
finally { 

     try{ 
      rs.close(); 
      pst.close(); 

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

     } 

    } 
     } 

}

来源

2017-02-09 Zunairah bukhari

哪一行是显示的错误？ – affaz

你需要使用的getString等前致电ResultSet#next()：

String sql ="select * from Deductions where emp_id = '"+value1+"'"; 
    pst=conn.prepareStatement(sql); 
    rs=pst.executeQuery(); 
    if(rs.next()) {    // here 
     String val = rs.getString(5); 
     String reason = rs.getString(6); 
    }

next()调用每次将光标向前移动一行。结果集光标初始位于之前第一行;下一个方法的第一个调用使第一行成为当前行;第二次调用使第二行成为当前行，依此类推。

来源

2017-02-09 09:22:02 GurV

空的resul设置非法opertion .. –

添加这些行后，这个错误来.. –

您是否尝试后，我最近更新的答案或之前？你现在可以试试吗？ – GurV

java.sql.SQLException：开始之前的结果集...如何删除此错误

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