Question

import java.sql.*;
import java.util.*;

public class app1conn {
String url="jdbc:mysql://localhost:3306/test",uname,password;
Connection con;
PreparedStatement ps;

app1conn() throws SQLException{

   DriverManager.registerDriver(new com.mysql.jdbc.Driver());
   con= DriverManager.getConnection(url,"root","");

}

public void insert (String name,String email,String age,String dob)throws Exception{


     ps=con.prepareStatement(url);
    //ps=new con.PreparedStatement ("insert into info(name,email,age,dob) values(?,?,?,?)") ;
    ps.setString(1,name);
    ps.setString(2,email);
    ps.setString(3,age);
    ps.setString(4,dob);
    ps.executeUpdate();

    }
public Vector getData() throws SQLException{
    ps=con.prepareStatement("Select * from info");
    ResultSet rs=ps.executeQuery();
    ResultSetMetaData rms=rs.getMetaData();
    Vector data=new Vector();

    while(rs.next()){

        Vector temp=new Vector();
        temp.add(rs.getString(1));
        temp.add(rs.getString(2));
        temp.add(rs.getString(3));
        temp.add(rs.getString(4));
        temp.add(rs.getString(5));


        data.add(temp);

    }
    return data;
}

 public Vector getDataById(String id) throws SQLException{
    ps=con.prepareStatement("Select * from info where id=?");
    ps.setInt(1,Integer.parseInt(id));
    ResultSet rs=ps.executeQuery();
    ResultSetMetaData rms=rs.getMetaData();
    Vector data=new Vector();

    while(rs.next()){

        Vector temp=new Vector();
        temp.add(rs.getString(1));
        temp.add(rs.getString(2));
        temp.add(rs.getString(3));
        temp.add(rs.getString(4));
        temp.add(rs.getString(5));


        data.add(temp);

    }
    return data;
 }
    void update_info(String name,String email,String age,String dob,String id) throws SQLException{
        ps=con.prepareStatement ("update info set name=?,email=?,age=?,dob=? where id=?");
        ps.setString(1, name);
        ps.setString(2, email);
        ps.setString(3, age);
        ps.setString(4, dob);


        ps.executeUpdate();
    }

}

我正在尝试插入数据.. 当我点击提交按钮..

它将null显示为输出..

Answer 1

String insertSQL = "insert into info(name,email,age,dob) values(?,?,?,?)";
PreparedStatement ps = dbConnection.prepareStatement(insertSQL);
    ps.setString(1,name);
    ps.setString(2,email);
    ps.setString(3,age);
    ps.setString(4,dob);
    ps.executeUpdate();

或者

String insertTableSQL = "INSERT INTO DBUSER"
        + "(USER_ID, USERNAME, CREATED_BY, CREATED_DATE) VALUES"
        + "(?,?,?,?)";
PreparedStatement preparedStatement = dbConnection.prepareStatement(insertTableSQL);
preparedStatement.setInt(1, 11);
preparedStatement.setString(2, "abc");
preparedStatement.setString(3, "system");
preparedStatement.setTimestamp(4, getCurrentTimeStamp());
// execute insert SQL stetement
preparedStatement .executeUpdate();

请参阅this article

Answer 2

你有没有跟踪你的代码，你在哪一行得到空值???

尝试使用此代码代替您的代码。

public boolean insert (String name,String email,String age,String dob){
 PreparedStatement preparedStatement;
 try{
 preparedStatement = con.prepareStatement("insert into info(name, email, age, dob) values(?,?,?,?)");
 preparedStatement.setString(1,name);
 preparedStatement.setString(2,email);
 preparedStatement.setString(3,age);
 preparedStatement.setString(4,dob);
 preparedStatement.executeUpdate();
 }
 catch (Exception e) {
    return false;
 }
   return true;
}

在mysql数据库中使用servlet插入数据

2 个答案: