java中占位符实现对Mysql数据库进行查询

java中占位符实现对Mysql数据库进行查询

System.out.println("请输入学号、密码：");

String sno,key;

Scanner scan1=new Scanner(System.in);

sno = scan1.nextLine();

key = scan1.nextLine();

StringBuffer sql = new StringBuffer();

sql.append("SELECT pw FROM user WHERE identity='student' AND id=? AND pw=?;");

pstm = con.prepareStatement(sql.toString());

pstm.setString(1, sno);

pstm.setString(2, key);

rs = pstm.executeQuery(sql.toString());

运行错误 

 解决办法

rs = pstm.executeQuery(sql.toString());改为rs = pstm.executeQuery();