Question

这是我正在编写的用于管理PostgreSQL的小型JSP servlet的代码片段，JSP声称它无效。

<% if (request.getParameter("student-id") != null && 
    request.getParameter("sname") != null && 
    request.getParameter("date-of-birth") != null && 
    request.getParameter("email") != null && 
    request.getParameter("level") != null) {
        String update = "UPDATE students SET name = '" + request.getParameter("sname") + "', " +
        "date_of_birth = '" + request.getParameter("date-of-birth") + "', " +
        "email = '" + request.getParameter("email") + "', " +
        "level = '" + request.getParameter("level") + "' " +
        "WHERE student_id = " request.getParameter("student-id");
        statement.executeUpdate(update);
} %>

出于某种原因，这引发了一个令人讨厌的错误，抱怨缺少分号：

An error occurred at line: 65 in the jsp file: /students.jsp
Generated servlet error:
Syntax error, insert ";" to complete BlockStatements

第65行是我打开＆lt;％

的地方

Answer 1

在student_id =“在这个地方

之后缺少'+'

<% if (request.getParameter("student-id") != null && request.getParameter("sname") != null && request.getParameter("date-of-birth") != null && request.getParameter("email") != null && request.getParameter("level") != null) { String update = "UPDATE students SET name = '" + request.getParameter("sname") + "', " + "date_of_birth = '" + request.getParameter("date-of-birth") + "', " + "email = '" + request.getParameter("email") + "', " + "level = '" + request.getParameter("level") + "' " + "WHERE student_id = "+ request.getParameter("student-id"); statement.executeUpdate(update); } %>

Answer 2

在这一行你忘了加号

"WHERE student_id = " request.getParameter("student-id");

我可以建议String.format()作为构建sql语句的更好，更清晰的方法

JSP认为我的条件是块语句

2 个答案: