Linking student to courses...

Ok, I managed to complete the student registration part and displaying the available courses, but now I'm struggling to link the student with a course, any advice?
I have my student submit info and course info on the same page, the problem I have is that the student number gets created when the info is submitted so how can I get the number at the same time when it is being created and use it in the course_student table? Any advice?

Try this...
After insertion into the student table, use this code to retrieve the sno which is the primary key

Language: PHP
$lastid=mysql_insert_id();

After that, insert into the course_student table using $lastid.

If that isnt clear enough, try to check this link out and read more about it [php.net] cheers!
sorry needed to edit... check this out also [www.w3schools.com]

Another way is to SELECT sno FROM student WHERE idno = $idnum

An ID number will always be unique...so it's another way to get the sno value.

Ok, so it seems I'll have to retrieve the number as soon as it is created, I'll try some methods out, thanks.
I think I'll use mysql_insert_id()

However, if you use Bigint for the id field, it might cause problems:

Quote
mysql_insert_id() will convert the return type of the native MySQL C API function mysql_insert_id() to a type of long (named int in PHP). If your AUTO_INCREMENT column has a column type of BIGINT (64 bits) the conversion may result in an incorrect value. Instead, use the internal MySQL SQL function LAST_INSERT_ID() in an SQL query. For more information about PHP's maximum integer values, please see the integer documentation.

How do you create the third linking table???? So lost>>>help!!!!

?

@Steve 77593448

The table that links courses and students already exists and it should get updated each time a student registers:

Language: PHP
<?php
 
	  //inserts an associative array into a table
 
	  function add_to_table($arrdata, $tablename){
 
		  foreach($arrdata as $key=>$value){
			  $keys[] = '`' . $key . '`';
			  $values[] = "'" . mysql_real_escape_string($value) . "'";
		  }
 
		  $key_list = join(',', $keys);
		  $value_list = join(', ', $values);
		  $SQL = "INSERT INTO `" . $tablename . "` (" . $key_list . ") VALUES (" . $value_list . ")";
		  $result = mysql_query($SQL);
	  }
 
  // adds info into course_student table right after info has been added to student table
				  $snum=mysql_insert_id();
 
				  for($i=0; $i <= $numcourses; $i++){
					$courses="course".$course_ids[$i];
 
					if (isset($_POST[$courses])){
						$link=array('sno'=>$snum,'cid'=> $course_ids[$i],'year'=> date('Y'));
						add_to_table($link,'course_student');
					}
 
				  }
 
?>

i didnt even know about this function i did it differently, but it works

77553055 Wrote:
-------------------------------------------------------
> Try this...
> After insertion into the student table, use this
> code to retrieve the sno which is the primary key
>
>

Language: PHP
> $lastid=mysql_insert_id();
>

> After that, insert into the course_student table
> using $lastid.

77528204 Wrote:
-------------------------------------------------------
> The table that links courses and students already
> exists and it should get updated each time a
> student registers:
>
>

Language: PHP
> <?php
> 	  
> 	  //inserts an associative array into a table
> 	  
> 	  function add_to_table($arrdata, $tablename){
> 		  
> 		  foreach($arrdata as $key=>$value){
> 			  $keys[] = '`' . $key . '`';
> 			  $values[] = "'" .
> mysql_real_escape_string($value) . "'";
> 		  }
> 		  
> 		  $key_list = join(',', $keys);
> 		  $value_list = join(', ', $values);
> 		  $SQL = "INSERT INTO `" . $tablename . "` (" .
> $key_list . ") VALUES (" . $value_list . ")";
> 		  $result = mysql_query($SQL);
> 	  }
> 
>   // adds info into course_student table right
> after info has been added to student table
> 				  $snum=mysql_insert_id();
> 				  
> 				  for($i=0; $i <= $numcourses; $i++){
> 					$courses="course".$course_ids[$i];
> 					
> 					if (isset($_POST[$courses])){
> 						$link=array('sno'=>$snum,'cid'=>
> $course_ids[$i],'year'=> date('Y'));
> 						add_to_table($link,'course_student');
> 					}
> 					
> 				  }
> 
> ?>
>

Before you execute the for loop for the courses, is there a way you can check how many elements in that before you execute it?

Quote
Before you execute the for loop for the courses, is there a way you can check how many elements in that before you execute it?

I'm not sure what you mean but I'm guessing its, "check how many courses are there"?

For that I have this function:

Language: PHP
//retrieve data from course table by field
 
	  function course_data($fieldname){
 
		  $result = mysql_query("SELECT ".$fieldname." FROM course");
 
		  while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
			  $arrdata[] =  $row[$fieldname];
		  }
 
		  return $arrdata;	 
	  }
 
                  $course_ids=array();
		  $course_ids=course_data('cid');
		  $numcourses=count($course_ids)-1;

Then I use $numcourses to do the loop

Nice one, now i see where $numcourses come from.