getting a last inserted varchar id which is an primary key - php

Question

I have multiple table ,which has to be inserted using different forms and all table have one id which is primary key and its varchar (NOT NULL),So i have one class function named as id_calc($tbl,$id) where $tbl is a parameter with table name and $id is a field id .And each time while inserting this function has to be called for id.
for example: If my id is "web1" ,next when i insert it shud give "web2","web3"...... i have tried with LAST_INSERT_ID() but its not working.so i tried with fetching the max(id) and splitting the string and variable but is also giving some problem.so how can i do this.please help!!!
class first{
public function id_calc($tbl,$id)
{
$sql = mysql_query("SELECT max($id) FROM $tbl where $id like '%web%'");
if($sql)
{
while ($row = mysql_fetch_assoc($sql))
{
$user=$row;
$a=implode(" ",$user);
}
$pattern = "/(\d+)/";
$array = preg_split($pattern, $a, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);
$new[]=$array['0'];
$new[]=$array['1']+1;
$result=implode("",$new);
return $result;
}
}
}
this function is called like
public function insertreport1()
{
$obj=new first();
$id=$obj->id_calc(tablename,idfield);
//insert query
}
this is my table structure
CREATE TABLE `report` (
`inc_id` varchar(25) NOT NULL,
`inc_status` int(11) NOT NULL,
`inc_date` datetime NOT NULL,
`inc_Name` varchar(45) NOT NULL,
`inc_Age` int(11) NOT NULL,
`inc_Gender` varchar(45) NOT NULL,
`inc_Mobile` varchar(45) NOT NULL,
`inc_Address` varchar(250) NOT NULL,
`inc_treatment` varchar(45) DEFAULT NULL,
`inc_userid` varchar(10) NOT NULL,
`inc_repTime` datetime NOT NULL
PRIMARY KEY (`inc_id`),
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

Answer 1

i think you can do it this way..write the query as
"SELECT MAX(CAST(SUBSTRING($id,4,12) AS UNSIGNED)) FROM $tbl WHERE $id LIKE '%web%'"
and then increment the id as web+(max+1).

Answer 2

Pseudo implementation would be
alter table definition
alter table `table` add column id int(11) not null auto_increment
change code
public function id_calc($tbl,$idcol) {
$sql = mysql_query("SELECT id FROM $tbl order by id desc limit 1");
if($sql){
while($row = mysql_fetch_assoc($sql));
$id = isset($row['id']) ? $row['id'] + 1 : 1;
return "{$idcol}{$id}";
}
}
Hope this helps