当我要在课堂上执行2个查询时，我遇到了问题 只有第一个查询正在执行，帮我解决问题 我在下面尝试了一些编码
public class DamageCopyingData extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String damageIssuePeriod = request.getParameter("DamageIssuePeriod");
String damageTrNo = request.getParameter("DamageTrNo");
int Dno = Integer.parseInt(damageTrNo);
String returnNo = request.getParameter("ReturnNo");
int Rno = Integer.parseInt(returnNo);
String returnDate = request.getParameter("ReturnDate");
String returnRef = request.getParameter("ReturnRef");
String voucherNo = request.getParameter("VoucherNo");
int vno = Integer.parseInt(voucherNo);
try {
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306", "root", "dinga");
PreparedStatement ps = con.prepareStatement("INSERT INTO project.damagereturn(TransactionType,VoucherNo,VoucherDate,VoucherRef,Salesman,SalesRoute,Location,IssuetoCostCentre,Description,PrintCost,ProductNo,PackSize,CostPrice,DamageType,QtyPack,QtyPcs,Weight,ToWeight,TotalAmount,Total,ProductName,BatchNo,ExpiryDate,UOM,OnHandPacks,OnHandPieces) SELECT * FROM project.damagevoucher WHERE VoucherNo =?");
ps.setInt(1, vno);
int rs = ps.executeUpdate();
System.out.println("value rs"+rs);
System.out.println("success...1");
if (rs==1) {
PreparedStatement ps1 = con.prepareStatement("Update project.damagereturn(DamageIssuePeriod,DamageTrNo,ReturnNo,ReturnDate,ReturnRef) values(?,?,?,?,?)");
ps1.setString(1, damageIssuePeriod);
ps1.setInt(2, Dno);
ps1.setInt(3, Rno);
ps1.setString(4, returnDate);
ps1.setString(5, returnRef);
int rs1 = ps1.executeUpdate();
System.out.println("value rs1"+rs1);
System.out.println("success...2");
}
} catch (Exception e2) {
e2.printStackTrace();
}
}
}