Other method is to add those two lines in your wp-config.php :
define('WP_SITEURL', 'http://example.com/');
define('WP_HOME', 'http://example.com/');
Then copy the files from blog.example.com to example.com dir and finally replace all urls in database. You can do this with php script:
<?php
// edit this line to add old and new terms which you want to be replaced
$search_replace = array( 'http://blog.example.com' => 'http://example.com');
//change the localhost,username,password and database-name according to your db
mysql_connect("localhost", "root", "rootpass") or die(mysql_error());
mysql_select_db("exampledb") or die(mysql_error());
$show_tables = mysql_query( 'SHOW TABLES' );
while( $st_rows = mysql_fetch_row( $show_tables ) ) {
foreach( $st_rows as $cur_table ) {
$show_columns = mysql_query( 'SHOW COLUMNS FROM ' . $cur_table );
while( $cc_row = mysql_fetch_assoc( $show_columns ) ) {
$column = $cc_row['Field'];
$type = $cc_row['Type'];
if( strpos( $type, 'char' ) !== false || strpos( $type, 'text' ) !== false ) {
foreach( $search_replace as $old_string => $new_string ) {
$replace_query = 'UPDATE ' . $cur_table .
' SET ' . $column . ' = REPLACE(' . $column .
', \'' . $old_string . '\', \'' . $new_string . '\')';
mysql_query( $replace_query );
}
}
}
}
}
echo 'replaced';
mysql_free_result( $show_columns );
mysql_free_result( $show_tables );
// mysql_close( $mysql_link );
?>
Good luck!