whats wrong with this query

[k994519]

hi guys this query does not seem to work

please help

 
$query =("UPDATE students SET ".$mod." = '".$_POST['box'][$i]."' where student_id='".$id."'");

all the other varibles are declared.......... ( I have not shown though though.....)

although the varible id is passed from a previous page and it is also printed to check that it is correct, the update does not happen.....

any help with be great thanks....

[BooRadLey]

hello, maybe try this out, I think when you pass a variable in '' it is used as a string:

$query =("UPDATE students SET ".$mod." = '".$_POST['box'][$i]."' where student_id=".$id);

I say to try this because with where student_id = a string may be the thing that is stopping it from updating since no such record exists. I hope this helps.

Brad

[k994519]

brad thanks for your help but it does not work.....

let me paste all my code here maybe you will get to understand it better .

<?php  

global $link;


echo $id;// need to get id of student 
print"<BLOCKQUOTE><center><H1>Add/ Update Student Modules </H1>";
print "<H2>Please select 8 modules</H2>";

if(isset($_POST['id'])) 
    { 
     field_validator("student", $_POST["id"], "number", 1,7); 

if( !($row =  check_sid($_POST['id'])) ) 

    { 
    // StudentID does not exist, create an error message: 
        $messages[]="  Student ID does not exist please, try again"; 
    }             

} 

?><form action="<?=$_SERVER["PHP_SELF"]?>" method="POST"> 

<?php  

$query=("select module_id, description from modules,students where students.student_id='".$id."' and modules.level = students.current_level order by module_id");  

// Run query:   this query works..........

$result=mysql_query($query, $link) or die("MySQL query $query failed.  Error if any: ".mysql_error());  

print("<table align=center>");
while($row = mysql_fetch_row($result))   

{   

     print"<Tr ><TD>";
	 echo "<input type=checkbox name=box[] value=" . $row[0] . ">" . $row[1] . "<br>";  

	 print"</Tr></TD>";	
}  

Print "</table><br>";


if(isset($_POST["submit"]))   

{ 

			// registration ok, get user id and update db with new info:
if(empty($messages)) 
	{
		if (count($_POST["box"]) != 8 )   
		{   
			print"<UL><li>Ensure u have selected 8 options!</UL></li>";
			print"<UL><li>Please Click back to make changes</UL></li><br>";   
		}   
		else   
		{   
			for ($i = 0; $i<8; $i++)   
				{   
					$b=$i+1; 
					$mod="module_id".$b;  // need to change database so module_id is module_id1 
					echo $id; echo'c';
					echo "Module choice  ".$b."  is set to Module ID " . ($_POST["box"][$i]) . "</br>";  
// this query should take in the value ".$ID." but it does not and i dont know why.......	
			$query1 =("UPDATE students SET ".$mod." = '".$_POST['box'][$i]."' where student_id='".$id."'");  
					$result=mysql_query($query1, $link) or die("Died inserting new student info into db.  Error returned if any: ".mysql_error());   
					//echo $query1."<br>";// for testing remove when finished 
		        }
		}
	}		
else 
	{
		displayErrors($messages);
	}	
}
?>    



<input name="submit" type="submit" value="Submit">&nbsp;<input type="reset" name="Reset" value="Reset">

</BLOCKQUOTE></center>
</form>
</html>

thanks for any help given.......

[laserlight]

hmm... why do you surround the string in parentheses?

$query = "UPDATE `students`
	SET `$mod`='{$_POST['box'][$i]}'
	WHERE `student_id`='{$id}'";

$result = mysql_query($query, $link)
	OR die(mysql_error()); //for debugging