How to Validate button click?

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PHP

jQuery

Hi all,
I am creating a table dynamically on a button click but while i am trying to put a validation like if any field of the previous row is blank, next row could not be created on button click and show an alert msg please fill all information of previous row.
Here is the code

<SCRIPT>
    RowCount=0;
    stat=false;
    function AddRow()
    {
 //$("#message").hide();
 
        jQtable=$('#SaleTable');
        jQtable.each(function()
        {
 var count=RowCount+1;
            var LastRow="<tr><td align="center"><INPUT TYPE='text' value='"+count+"' disabled='disabled' name='Slno_"+RowCount+"' id='Slno_"+RowCount+"' size=1></td><td align="center"><INPUT type='checkbox' name='in_travel_"+RowCount+"' ID='in_travel_"+RowCount+"' value='in_terval'  size=10></td><td align="center"><INPUT type='text' name='date_"+RowCount+"' ID='date_"+RowCount+"' size=10></td><td align="center"><textArea name='cities_visit_"+RowCount+"' ID='cities_visit_"+RowCount+"' cols=10></textArea></td><td align="center"><select id='reimbursement_"+RowCount+"' name='reimbursement_"+RowCount+"'><option selected='selected' value='None'>--None--</option><option value='DA'>DA</option><option value='Ticket'>Ticket</option><option value='Misc'>Misc</option></select></td><td align="center"><INPUT  type='text' name='amount_"+RowCount+"' ID='amount_"+RowCount+"' size=10></td><td align="center"><textArea name='Remark_"+RowCount+"' ID='Remark_"+RowCount+"' cols=10></textArea></td><td align="center"><INPUT style='text-align:right' type='checkbox' name='bills_"+RowCount+"' ID='bills_"+RowCount+"' value='bills' size=10></td><td align="center"><INPUT style='text-align:right' type='submit' name='submit_"+RowCount+"' ID='submit_"+RowCount+"' onclick='getvalue()' value='Submit' size=10><p id="message_"+RowCount+"" name="message_"+RowCount+"" style="color:#CC0000;"></p></td><td align="center"></td></tr>";
         // $(this).append(LastRow);
 
 
  $(LastRow).find(':submit').click(getvalue).end().appendTo('#SaleTable');
            });
 RowCount++;
 
     }
    function removeTableRow()
    {
        jQtable=$('#SaleTable');
        if(RowCount > 0)
        {
            jQtable.each(function()
            {
                if($('tbody', this).length > 0)
                {
                    $('tbody tr:last', this).remove();
                }
                else
                {
                    $('tr:last', this).remove();
                }
            });
            RowCount--;
        }
 
    }
 
 
 
 ///corredt one
 function getvalue() {
     var row = $(this).closest('tr');
 if($('select[name="month"]').val()=="")
 {
 //alert("Please select a Month!");
//  var row = $(this).closest('tr');
 $('p[name^="message_"]', row).html('Please select a Month!');
    $('p[name^="message_"]', row).hide();
    $('p[name^="message_"]', row).fadeIn(1500);
 $('select[name="month"]').focus();
//$('input:submit[name="addrow"]').attr("disabled", "disabled");
//$("#addrow").attr("disabled", "disabled");
 return false;
 }
 if($('input:text[name^="date_"]', row).val()=="")
{
 $('p[name^="message_"]', row).html('Please Fill a Date!');
    $('p[name^="message_"]', row).hide();
    $('p[name^="message_"]', row).fadeIn(1500);
 $('input:text[name^="date_"]', row).focus();
 return false;

}
if($('textarea[name^="cities_visit_"]', row).val()=="")
{
 $('p[name^="message_"]', row).html('Please Fill Cities Visited!');
    $('p[name^="message_"]', row).hide();
    $('p[name^="message_"]', row).fadeIn(1500);
 $('textarea[name^="cities_visit_"]', row).focus();
 return false;

}   
if($('select[name^="reimbursement_"]', row).val()=="" || $('select[name^="reimbursement_"]', row).val()=="None")
{
 $('p[name^="message_"]', row).html('Please Select Reimbursement Type!');
    $('p[name^="message_"]', row).hide();
    $('p[name^="message_"]', row).fadeIn(1500);
 $('select[name^="reimbursement_"]', row).focus();
 return false;

}
if($('input:text[name^="amount_"]',row).val()=="")
{
 $('p[name^="message_"]', row).html('Please Fill Amount!');
    $('p[name^="message_"]', row).hide();
    $('p[name^="message_"]', row).fadeIn(1500);
 $('input:text[name^="amount_"]',row).focus();
 return false;

}
if($('textarea[name^="Remark_"]', row).val()=="")
{
 $('p[name^="message_"]', row).html('Please Fill Remark!');
    $('p[name^="message_"]', row).hide();
    $('p[name^="message_"]', row).fadeIn(1500);
 $('textarea[name^="Remark_"]', row).focus();
 return false;

}
  var month = $('select[name="month"]').val();
    var sl = $('input:text[name^="Slno_"]', row).val();
  //  var in_tra = $('input[name^="in_travel_"]:checked', row).val();
 if($('input[name^="in_travel_"]', row).is(':checked'))
 {
  var in_tra="Yes";
 }
 else
 {
  var in_tra="No";
 }
   
  var date = $('input:text[name^="date_"]', row).val();
   
 var cities = $('textarea[name^="cities_visit_"]', row).val();

    var rm_type = $('select[name^="reimbursement_"]', row).val();

 var remarks = $('textarea[name^="Remark_"]', row).val();

 var amount=$('input:text[name^="amount_"]',row).val();
 
 //var bills = $('input[name^="bills_"]:checked', row).val();
 
 if($('input[name^="bills_"]', row).is(':checked'))
 {
  var bills="Yes";
 }
 else
 {
  var bills="No";
 }
 
 var row1=RowCount;
//alert(RowCount);
 $.post('add-data-sql.php', {sl: sl, in_tra: in_tra, date: date, cities: cities, rm_type: rm_type, remarks: remarks,amount: amount, bills: bills , row: row1,month:month},
function(data){
//$("#message_").html(data);
//$("#message").hide();
//$("#message").fadeIn(1500); //Fade in the data given by the insert.php file 'message_"+RowCount+"'
$('p[name^="message_"]', row).html(data);
$('p[name^="message_"]', row).hide();
$('p[name^="message_"]', row).fadeIn(1500);

});
 
 
}

</SCRIPT>

here is the button

<INPUT type="submit" id="addrow" name="addrow" value="Add" onclick='AddRow()'>

Thanks