Flatfile DB help

jzee

hope someone can help with this.

I am trying to create a a flatfile database which stores a line number as a unique id

Example:

and so on...

im have trouble trying to get the next save location, when an entry has been removed.

Example:

if entry 2 has been removed & the next entry is saved it is saved as

5 instead of 2.

I've tried a number of things but all fail.

i have tried doin this with a function

example:


$x =1; 


function FindNextID($z)
{
$ffile = "dbfile.dat";
$fdata = file($ffile);
for ($q = 0; $q < sizeof($fdata); $q++)
{
list ($id, $name, $email, $date) = explode("|", trim($fdata[$q]));
if ($id >= $z)
{
$z = $id+1;
}
}
DoSave($z);   // Take the next ID and save
}

FindNextID($x);

This code will find the next id location but does not take into account if id 2 is missing

so i tried somethin like this

$x =1;

function FindNextID($z)
{
$dosave = 1;
$ffile = "dbfile.dat";
$fdata = file($ffile);
for ($q = 0; $q < sizeof($fdata); $q++)
{
list ($id, $name, $email, $date) = explode("|", trim($fdata[$q]));

if ($id == $z)
{
$dosave = 0;
$z = $z+1;
FindNext($z);
}
}
if ($dosave)
{
DoSave($z);
}
}

FindNextID($x);  // can be called from another function

this is as close as i can get .... it does save the next location but!!

after about 2 saves it does mental lol! and saves the same data over again with a new id

I know there is somethin missing but not sure what

any help would be great

thanks!!

PS .. please note i have not entered global $var as i didnt feel the need in the demo :p

Weedpacket

If you read through the table and get all the IDs into an array called $ids, then the first unused id would be

min(array_diff(range(min($ids), max($ids)), $ids))

unless the first missing ID is 1.
But you'll note that in most well-designed databases, IDs aren't recycled anyway.

jzee

hi weed

cheers for postin

i will have a play with that

im not doin to save the data in a single file now as i dont think its very stable if there are many entries

instead save each line of code to its own file

example:

1 | $Name | $Email | $Date |

would be placed into file

file_1.dat

this way 1 can be given a variable $id

so getting the next id to save next data

example:


$x=1;

// Check if file already exists - Start
function checkfile($id)
{

$fpath = "file-$id.dat";    // Save File

if (file_exists($fpath))    // Does the ID already exist?
{
$id++;                      // Yes! so increase it
$x = $id;
checkfile($x);              // Check the new id
}
else
{
dosave ($fpath);            // Found new ID save it!
}
}
// Check if file already exists - End


checkfile($x);

Just an idea im playing with