PreparedStatement的用法

package com.example.jdbc.origin;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Statement;

public class Test {
	public static void main(String[] args) throws SQLException {
        try
        {
            Class.forName("com.mysql.cj.jdbc.Driver");//加載並注冊驅動程序
        }catch(ClassNotFoundException e)//加載錯誤，捕獲異常
        {
            System.out.println("加載驅動失敗");
        }
          	Connection con =DriverManager.getConnection("jdbc:mysql://localhost:3306/user?Unicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true&serverTimezone=UTC", "root","123456"); //創建Connection連接對象
          	String name="batch insert test name100";
          	String sql0="update t_person set job=(select count(*) from t_user where user_name='"+name+"') where name='"+name+"'";
          	Statement sta = con.createStatement();
          	System.out.println("sql0:"+sql0);
          	sta.execute(sql0);
          	String sql="update t_person set job=(select count(*) from t_user where user_name=?)as job where name=?";
        	sql="update t_person set job=? where name= ?";
        	System.out.println("sql:"+sql);
          	PreparedStatement stmt = con.prepareStatement(sql); //創建語句對象
          	stmt.setString(1, name);
          	stmt.setString(2, name);
          	//stmt.execute();
          	stmt.executeUpdate();
            con.close();
             
    }

}