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");//加载并注册驱动程序
        }catch(ClassNotFoundException e)//加载错误，捕获异常
        {
            System.out.println("加载驱动失败");
        }
          	Connection con =DriverManager.getConnection("jdbc:mysql://localhost:3306/user?Unicode=true&characterEncoding=UTF-8&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true&serverTimezone=UTC", "root","123456"); //创建Connection连接对象
          	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); //创建语句对象
          	stmt.setString(1, name);
          	stmt.setString(2, name);
          	//stmt.execute();
          	stmt.executeUpdate();
            con.close();
             
    }

}