如何动态创建表并在不存在列时更改表

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 ).