JavaのJDBC文インタフェース単純なSQL文のコール

public class Demo2 {

public static void main(String[] args) {
    try {
        Class.forName("com.mysql.jdbc.Driver");
        Connection conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","dyl123");

        //使用statement接口实现简单sql调用
        Statement stmt=conn.createStatement();

        String sql="insert into t_user(username,pwd,regTime) values ('赵六',66666,now()) ";

        //传入外界参数，需要拼字符串
        String name="钱七";
        String sql2="insert into t_user(username,pwd,regTime) values('"+name+"',6666,now())";

        stmt.execute(sql);
        stmt.execute(sql2);

    //sql注入，传参的几种拼接方式,如果代码传参有问题，则数据库会被侵入
        String id="4";

        String sql3="delete from t_user where id=4";
        String sql4="delete from t_user where id='"+id+"'";
        String sql5="delete from t_user where id="+id;

        stmt.execute(sql4);

    } catch (SQLException e) {
        e.printStackTrace();
    } catch (ClassNotFoundException e) {

        e.printStackTrace();
    }

}
}