PHP 创建数据库练习

<?php
header("Content-type:text/html","Charset=UTF-8");
$file="config/config.php";
if(is_writable($file)!=null){
 echo "文件可写入 \n";
}else{
 echo "文件不可写|";
 exit();
}
if(isset($_POST["install"])){
 $string = "<?php \n";
 $string .="\$mysql_host=\"$_POST[db_host]\";\n";
 $string .="\$mysql_user=\"$_POST[db_user]\";\n";
 $string .="\$mysql_pass=\"$_POST[db_pass]\";\n";
 $string .="\$mysql_dbname=\"$_POST[db_dbname]\";\n";
 $string .="\$mysql_tag=\"$_POST[db_tag]\";\n";
 $string .= "?>";
 if($f=fopen($file,"w+")){
  echo "文件已打开|";
  if(fwrite($f,$string)===false){
   echo "文件无法与入";
   exit();
  }
  else{
   echo "文件写入成功";
   include_once($file);
   if($link = mysql_connect($mysql_host,$mysql_user,$mysql_pass)or die("数剧库链接失败")){
    mysql_query("CREATE DATABASE `$mysql_dbname` CHARACTER SET utf8 COLLATE utf8_general_ci");
    if(mysql_select_db($mysql_dbname)){
     echo "|数据库创建成功|";
    $mysql_add_table[]= "CREATE TABLE `".$mysql_tag."j1`(
      `id` int(8) unsigned NOT NULL AUTO_INCREMENT,
      `username` varchar(15)  CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
         `types` varchar(60) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
          PRIMARY KEY (`id`)
        );";
    $mysql_add_table[]= "CREATE TABLE `".$mysql_tag."j2`(
      `id` int(8) unsigned NOT NULL AUTO_INCREMENT,
      `username` varchar(15)  CHARACTER SET utf8 COLLATE