Wednesday, 24 October 2012

PHP: Export Database Schema as XML

Sometimes it can be useful to have a dump of the current database schema. The script below reads the schema from a MySQL database and outputs XML that describes the schema.

At first we connect to a MySQL database and use the SHOW TABLES command to return all the tables in the database. Next, we iterate over each table and return the fields for each table using the SHOW FIELDS command. Finally, we put all of the returned information into XML.
Have a look at the code:
// database constants
// make sure the information is correct
define("DB_SERVER", "localhost");
define("DB_USER", "root");
define("DB_PASS", "password");
define("DB_NAME", "tutorials");

// connection to the database 
$dbhandle = mysql_connect(DB_SERVER, DB_USER, DB_PASS) 
   or die("Unable to connect to MySQL"); 

// select a database to work with 
$selected = mysql_select_db(DB_NAME, $dbhandle) 
   or die("Could not select examples"); 

// return all available tables 
$result_tbl = mysql_query( "SHOW TABLES FROM ".DB_NAME, $dbhandle ); 

$tables = array(); 
while ($row = mysql_fetch_row($result_tbl)) { 
   $tables[] = $row[0]; 

$output = "<?xml version=\"1.0\" ?>\n"; 
$output .= "<schema>"; 

// iterate over each table and return the fields for each table
foreach ( $tables as $table ) { 
   $output .= "<table name=\"$table\">"; 
   $result_fld = mysql_query( "SHOW FIELDS FROM ".$table, $dbhandle ); 

   while( $row1 = mysql_fetch_row($result_fld) ) {
      $output .= "<field name=\"$row1[0]\" type=\"$row1[1]\"";
      $output .= ($row1[3] == "PRI") ? " primary_key=\"yes\" />" : " />";

   $output .= "</table>"; 

$output .= "</schema>"; 

// tell the browser what kind of file is come in
header("Content-type: text/xml"); 
// print out XML that describes the schema
echo $output; 

// close the connection