更新語句只運行一次。？

因此，我有一個問題，第一個查詢的結果只更新一次。更新語句只運行一次。？

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(); 

}

我試圖更新每個結果，因爲我遍歷了我的選擇查詢的結果。我要檢查一下，有多個學生在多個班級註冊，所以學生不止一次返回。

但是，學分只會在註冊表中的每個學生更新1（+3）。

請幫忙，謝謝！

來源

2011-10-09 Aziz

問題是，JDBC不允許同時對多個表進行表查詢，同時嘗試對這些表進行更改。

來源

2011-10-25 16:51:54 Aziz

您必須使用Updatable ResultSet。

來源

2011-10-09 03:33:53 adatapost

即時通訊仍然有點困惑..所以我要修改是聲明= con1.createStatement（ResultSet.CONCUR_UPDATABLE，ResultSet.TYPE_SCROLL_SENSITIVE）; – Aziz

更新語句只運行一次。？

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