String sess_user = session.getAttribute("userid").toString();
out.println(sess_user);
try{
String connectionURL = "jdbc:mysql://localhost:3306/books";// books is the database
Connection connection = null;
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(connectionURL, "root", "bonnysingh");
Statement st = connection.createStatement();
ResultSet rs=st.executeQuery("select email from signup where UserName = '" + sess_user +"'");
while(rs.next()){
userEmail = rs.getString(3);
}
}
catch(Exception ee){
out.println(ee);
}
out.println("Hello");
out.println(userEmail);
userEmail的輸出始終爲空。我不知道這裏有什麼問題,但我認爲while(rs.next())循環沒有正確執行。誰能告訴我最新的錯誤?此錯誤表示java.sql.SQLException:列索引超出範圍,3> 1
爲什麼你甚至認爲當你選擇一個列時,你應該用'getString(3)'檢索它的值? –