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[英]Prepared Statement seems to return always null in java servlet
[英]Servlet login with prepared statement
我尝试找出以下代码中的错误在哪里:
public void service(HttpServletRequest request, HttpServletResponse response){
try{
user1 = request.getParameter("nameLog");
pass1 = request.getParameter("passLog");
String userid = null;
String passdb = null;
String query = "select user, pass from login where `user` = ? and `pass`=?";
PreparedStatement pst = conn.prepareStatement(query);
ResultSet rs = pst.executeQuery();
pst.setString(1, user1);
pst.setString(2, pass1);
while(rs.next()){
userid = rs.getString("user1");
passdb = rs.getString("pass1");
pst.executeQuery();
}
if(userid.equals(user1)&& passdb.equals(pass1)){
response.sendRedirect("/WebContent/login/Main.html");
}
}catch(Exception ex){
ex.printStackTrace();
}
}
我尝试登录到我的应用程序(数据库列名称为user
和pass
),但出现错误:
java.sql.SQLException: No value specified for parameter 1
在这一行
ResultSet rs = pst.executeQuery();
如何摆脱此错误并登录到我的页面?
谢谢
订单很重要! 您需要在调用executeQuery
之前传递参数,如下所示:
PreparedStatement pst = conn.prepareStatement(query);
pst.setString(1, user1);
pst.setString(2, pass1);
ResultSet rs = pst.executeQuery();
您正在执行查询,然后再设置值。 它应该是:
PreparedStatement pst = conn.prepareStatement(query);
pst.setString(1, user1);
pst.setString(2, pass1);
ResultSet rs = pst.executeQuery();
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