Java Update语句只运行一次。？

所以我遇到了一个问题，第一次查询的结果只更新了一次

Statement statement = con1.createStatement();
    ResultSet qResult = statement.executeQuery("select e.Grade, e.StudentID, s.StudentID, s.Classification, s.CreditHours, s.GPA"+ " " +
                            "from Enrollment e, Student s" + " " +
                            "where e.StudentID = s.StudentID");

    double grade = 0.00;
    int tCredits = 0;
    float newGpa = 0;
    String nClass = "";
    PreparedStatement statement2;
    int rowCount = 0;
    String sId = "";
    //loop results
    while(qResult.next())
    {
        sId = qResult.getString(2);
        //1 parse grade - convert to double and save to variable
        grade = parseGrade(qResult.getString(1));
        //2 save Tcredit hours to var
        tCredits = qResult.getInt(5);
        //3 calc new GPA = ((gpa * tCred)+ (3 * grade))/(tCred +3)
        newGpa = (float) (((qResult.getDouble(6) * tCredits) + (3 * grade))/(tCredits + 3));
        //4 add 3 to Tcredit hours
        tCredits = tCredits + 3;
        //5 check tCredit hours and update classification
        nClass = getNewClass(tCredits);

        //6 Update Tables!!
        statement = con1.createStatement();
        rowCount += statement.executeUpdate("update Student" + " " +
                              "set Classification=" + "'" + nClass + "'" + ", GPA=" + newGpa +", CreditHours=" + tCredits  + " " +
                              "where StudentID=" + qResult.getString(2));

    }
    System.out.println("rows Changed:::: " + rowCount);
    //statement.close();

}

我试图在遍历select查询的结果时更新每个结果。 我已经检查过了，有多个学生在多个班级注册，所以学生确实会被返回不止一次

但是，对于登记表中的每个学生，学分仅更新1（+3）

请帮忙，

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谢谢

您必须使用ResultSet。

问题是JDBC不允许在试图同时更改多个表时从多个表中查询表。

我仍然有点困惑。。所以我要修改的就是statement=con1.createStatement（ResultSet.CONCUR\u updateable，ResultSet.TYPE\u SCROLL\u SENSITIVE）；