當用ResultSet接收來自資料庫查詢的結果集時，即使結果集只有一條資料，也需要用到resultSet.next()函式移動遊標獲取資料。

錯誤程式碼：

conn = DriverManager.getConnection(url, "briup", "briup");
			String sql = "select password from e_customer where name=?";
			pre = conn.prepareStatement(sql);
			pre.setString(1, username);
			resultSet = pre.executeQuery();
			String passwd = null ;
		    passwd= resultSet.getString(1);
			if(passwd.equals(password)&&password!=null) {
				flag = true;
			
 

修改後：

conn = DriverManager.getConnection(url, "briup", "briup");
			String sql = "select password from e_customer where name=?";
			pre = conn.prepareStatement(sql);
			pre.setString(1, username);
			resultSet = pre.executeQuery();
			String passwd = null ;
		    while (resultSet.next()) {
		    passwd= resultSet.getString(1);
			if(passwd.equals(password)&&password!=null) {
				flag = true;
			}