SQL INSERT problem - help please

Question

Hello,
I'm having a problem with INSERT statement.
There is a "ShowFinal.jsp" page, which is a list of candidates who selected from the second
interview. The user picked some candidates from the list and conduct the 3rd interview. After
he check suitable candidates(who are selected from the 3rd interview) from the list , enter
basic salary for every selected candidate, enter date of interview and finally submit the form.
These data should be save into these tables.
FinalSelect(nicNo,date)
EmpSalary(nicNo,basicSal)
In this "ShowFinal.jsp" page, it validates the following conditions using JavaScript.
1) If the user submit the form without checking at least one checkbox, then the system should be
display an alert message ("Please select at least one candidate").
2) If the user submit the form without entering the basic salary of that candidate which was
checked, then the system should be display an alert message ("Please enter basic salary").
These are working well. But my problem is how to wrote the "AddNewFinal.jsp" page to save these
data into the db.
Here is my code which I have wrote. But it points an error.
"AddNewFinal.jsp"
String interviewDate = request.getParameter("date");
String[] value = request.getParameterValues("ChkNicno");
String[] bs = request.getParameterValues("basicSal");
String sql ="INSERT INTO finalselect (nicNo,date) VALUES(?,?)";
String sql2 ="INSERT INTO EmpSalary (nicNo,basicSal) VALUES(?,?)";
for(int i=0; i < value.length; i++){
     String temp = value;     
     for(int x=0; x < bs.length; x++){
          String basic = bs[x];
          pstmt2 = connection.prepareStatement(sql2);
          pstmt2.setString(1, temp);
          pstmt2.setString(2, basic);
          int RowCount1= pstmt2.executeUpdate();
     pstmt1 = connection.prepareStatement(sql);
     pstmt1.setString(1, temp);
     pstmt1.setString(2, interviewDate);
     int RowCount= pstmt1.executeUpdate();
Here is the code for "ShowFinal.jsp".
<form name="ShowFinal" method="POST" action="AddNewFinal.jsp" onsubmit="return checkEmpty() &&
ValidateDate();">
<%--  Loop through the list and print each item --%>
<%
     int iCounter = 0; //counter for incremental value
     while (igroups.hasNext()) {
          Selection s = (Selection) igroups.next();
          iCounter+=1; //increment
%>
<tr>
     <td style="background-color:ivory" noWrap width="20">
     <input type="checkbox" name="<%= "ChkNicno" + iCounter %>"      
value="<%=s.getNicno()%>"></td>
        <td style="background-color:ivory" noWrap width="39">
             <%= s.getNicno() %>  </td>
     <td style="background-color:ivory" noWrap width="174">
          <input type="text" name="<%= "basicSal" + iCounter %>" size="10"> </td>
</tr>
<%
%>
Date of interview<input type="text" name="date" size="17"></td>
<input type="submit" value="APPROVE CANDIDATE" name="B1" style="border: 1px solid #0000FF">
</form>........................................................
Here is the error generated by TOMCAT.
root cause
java.lang.NullPointerException
     at org.apache.jsp.AddNewFinal_jsp._jspService(AddNewFinal_jsp.java:70)
     at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:137)
I have goto the file "AddNewFinal_jsp.java". The line 70 points to the following line.
for(int i=0; i < value.length; i++){ [/b]
Please can someone help me to solve this problem? Please help me to do this task.
Thanks.

Answer 1

Hi Casabianca ,
It is clearly that your problem is not on the database end, more like a servlet/jsp issue.
I will not comment on the javascript portion, but rather the 2 jsps.
a simple way to trace what's go wrong is to check the final result (the html code) of the first jsp (showFinal.jsp), and compare against what is expected by the 2nd jsp (AddNewFinal.jsp). Most browser do provide "view source" on the page visited.
the following code
<input type="checkbox" name="<%= "ChkNicno" + iCounter %>" value="<%=s.getNicno() %>">
<input type="text" name="<%= "basicSal" + iCounter %>"
would likely to be "translated" to html code something as follow:
<input type="checkbox" name=""ChkNicno0" value="nicNo>">
<input type="text" name="basicSal0">
the original code in "AddNewFinal.jsp" using
request.getParameterValues("ChkNicno");
which looking for a none exist http request parameter (sent as "ChkNicno0",etc but look for "ChkNicno"), which has explained before.
the second attempt to use String[] value = request.getParameterValues("ChkNicno" + iCounter); give Cannot resolove symbol :iCounter. because iCounter never defined in the 2nd jsp!
Most of the error message do give clue to cause of error... : )
not too sure on your intension, assume you wish to update only those selected (checked) row to db.
some suggestions:
1) <input type="text" name="ChkNicno" size="10"> </td>...
<input type="text" name="basicSal" size="10"> instead.
then use javascript to based on checked element index (refer to javascript spec for more details), for those index not checked, clear off the correspond index "basicSal" field value.
e.g. ChkNicno[1] is not checked, empty basicSal[1] value before submission.
This will give us only selected rows values.
2) retain the code
String[] value = request.getParameterValues("ChkNicno");
String[] bs = request.getParameterValues("basicSal");at 2nd jsp, as now the http request will pass parameters using "ChkNicno" and "basicSal".
3) some change to the code for optimization
for(int i=0; i < value.length; i++){
     String temp = value;     
     for(int x=0; x < bs.length; x++){
          String basic = bs[x];
          pstmt2 = connection.prepareStatement(sql2);
          pstmt2.setString(1, temp);
          pstmt2.setString(2, basic);
          int RowCount1= pstmt2.executeUpdate();
     pstmt1 = connection.prepareStatement(sql);
     pstmt1.setString(1, temp);
     pstmt1.setString(2, interviewDate);
     int RowCount= pstmt1.executeUpdate();
to
pstmt1 = connection.prepareStatement(sql);
pstmt2 = connection.prepareStatement(sql2);
for(int i=0; i < value.length; i++){
     String temp = value;     
     for(int x=0; x < bs.length; x++){
          String basic = bs[x];
          pstmt2.setString(1, temp);
          pstmt2.setString(2, basic);
          int RowCount1= pstmt2.executeUpdate();
     pstmt1.setString(1, temp);
     pstmt1.setString(2, interviewDate);
     int RowCount= pstmt1.executeUpdate();
preparestatement created once should be sufficient as we do not change the sql statement throughout the loop.
there are better solutions out there, this just some ideas and suggestions.Do try out if you wish.
Hope it helps. : )