how to create table dynamically and alter table when column not exists - php

Question

enter
<?php $dob=$_SESSION['dob'];
$month=$_SESSION['month'];
$exists = false;
$columns = mysql_query("show columns from $month");
while($c = mysql_fetch_assoc($columns)){
if($c['Field'] == $dob){
$exists = true;
break;
}
}
if(!$exists){
mysql_query("ALTER TABLE `$month` ADD `$dob` varchar(100) default absent");
}
$roll=$_SESSION['var'];
foreach( $roll as $value=>$roll) {
$name = mysql_real_escape_string ($roll);
$sql="insert into $month (roll) values ('$name')";
mysql_query($sql)or die(mysql_error());
}
?>
Q:-how to create a table and alter table in mysql php?

Answer 1

To create a table do:
CREATE TABLE `tableName` (
... Columns ...
);

Answer 2

cretae table:
CREATE TABLE <tablename> (<column_name <data_type>(length if_required), .... );
Alter Table:
ALTER TABLE <tablename> ADD <newcolumnname> <data_type>(length if_required);
ALTER TABLE <tablename> DROP <columnname>;
ALTER TABLE <tablename> MODIFY <columnname> <data_type>(length if_required);
Update table:
UPDATE <tablename> SET <columnname> = <value> WHERE(if_required) <condition>;

Answer 3

Maybe you need this? This ORM library allow you to develop DB schema on the flight. More here.

Answer 4

Or maybe you need so called CODE FIRST STYLE ORM LIBRARY FOR PHP? I know one but it creates/modifies/alters tables according to your class definitions:
For example if you have:
class user
{
public $id;
public $name;
}
Bu default it will create table user with fields id and name. Also that framework gives full control on field properties and table properties using doc comments. It is called db.php (http://db.php).