How to block inserting empty strings in MySQL - php

Question

I have this update statement (PHP code):
$sql1="UPDATE `utilizatori` " .
"SET utilizator='$utilizator', parola='$parola1', nume='$nume', " .
"`prenume='$prenume', varsta='$varsta', localitate='$localitate'` ";
WHERE parola='".$_SESSION['parola']."'";
This will update some MySQL table fields via an html form. The user wants to change just his name for instance. He completes just name field, then he presses submit. The data is sent into the table with the UPDATE statement above.
The problem is that it also updates the table with blank values that user didn't complete. I don't want the blank values to be added.
How can I block the blank values to be sent into the table?

Answer 1

If you really wanted to do this in the update, you can change the set statement to something like:
set utilizator = (case when '$utilizator' <> '' then '$utilizator' else utilizator end),
. . .
This will use the previous value if the new one is blank.
You can also do this at the application level by just updating the fields that have changed.
And, you should use parameterized queries rather than directly substituting values into a string. That is another issue, though.

Answer 2

You can do two things to solve this issue. One is to preload the data in the form. So when the user change his name, the other fields are already loaded with the original information.
The second option is to create an update query based on the fields have a value.
Example of option 1:
<?php
//
//GET THE DATA FROM A SELECT QUERY HERE
//FOR EXAMPLE: $sql = "SELECT * FROM `utilizatori` WHERE parola='".$_SESSION['parola']."'";
//Put the data of the sql row in a variable e.g. $sqlRow.
?>
<!--Use variable in your form!-->
<form>
...
...
<input name="nume" value="<?=$sqlRow['nume']?>"/>
<input name="utilizator" value="<?=$sqlRow['utilizator']?>"/>
...
...
</form>
Example of option 2:
<?php
//Catch post data
if($_POST)
{
$updateString = "";
foreach($_POST as $inputField => $inputValue)
{
if($inputValue != "")
{
$updateString .= $inputField." = '".$utilizator."',";
}
}
//Strip last ,
$updateString = substr($updateString,0,-1);
if($updateString != "")
{
//Your query would be
$sql1 = "UPDATE `utilizatori` SET ".$updateString." WHERE parola='".$_SESSION['parola']."'";
}
}
?>

Answer 3

$updateClauseArr = Array();
foreach($_REQUEST as $key => $val){
if(is_numeric($val)){
$updateClauseArr[] = '$key = '.(int) $val;
}else{
$updateClauseArr[] = "$key = '".htmlentities($val,ENT_QUOTES,'UTF-8')."'";
}
}
if(sizeof($updateClauseArr) > 0){
$updateSet = implode(',' ,$updateClauseArr);
$sql1="UPDATE `utilizatori` SET ".$updateSet." WHERE parola='".$_SESSION['parola']."'";
}

Answer 4

See what field values have been submitted by the user. then iterate in a loop for the fields that have value to make variable to be concatenated to the update query.