实用mysql数据库连接类

class mysql {
 private $db_host;     //主机地址
 private $db_user;     //用户名
 private $db_pass;     //连接密码
 private $db_name;     //名称
 private $db_charset;  //编码

 private $conn;
 private $query_id;   //用于判断sql语句是否执行成功
 private $result;     //结果集
 private $num_rows;   //结果集中行的数目，仅对select有效
 private $insert_id;  //上一步 insert 操作产生的 id

// 构造/析构函数
 function __construct ($db_host,$db_user,$db_pass,$db_name,$db_charset,$conn) {
 $this->db_host = $db_host ;
 $this->db_user = $db_user ;
 $this->db_pass = $db_pass ;
 $this->db_name = $db_name ;
 $this->db_charset = $db_charset ;
 $this->conn = $conn ;
 $this->connect();
 }

 function __destruct () {
 @mysql_close($this->conn);
 }

// 连接/选择数据库
 public function connect () {
 if ($this->conn == 'pconn') {
  @$this->conn = mysql_pconnect($this->db_host,$this->db_user,$this->db_pass);
 } else {
  @$this->conn = mysql_connect($this->db_host,$this->db_user,$this->db_pass);
 }
 if (!$this->conn) {
  $this->show_error('数据库-连接失败：用户名或密码错误！');
 }
 if (!@mysql_select_db($this->db_name,$this->conn)) {
  $this->show_error("数据库-选择失败：数据库 $this->db_name 不可用");
 }
 mysql_query("set names $this->db_charset");
 return $this->conn;
 }

// query方法
 public function query ($sql) {
 if ($this->query_id) $this->free_result();
 $this->query_id = @mysql_query($sql,$this->conn);
 if (!$this->query_id) $this->show_error("sql语句 "$sql" 执行时遇到错误");
 return $this->query_id;
 }

// 查询所有
 public function findall ($table_name) {
 $this->query("select * from $table_name");
 }

// mysql_fetch_array
 public function fetch_array () {
 if ($this->query_id) {
  $this->result = mysql_fetch_array($this->query_id);
  return $this->result;
 }
 }

// ......

 public function fetch_assoc () {
 if ($this->query_id) {
  $this->result = mysql_fetch_assoc($this->query_id);
  return $this->result;
 }
 }

 public function fetch_row () {
 if ($this->query_id) {
  $this->result = mysql_fetch_row($this->query_id);
  return $this->result;
 }
 }

 public function fetch_object () {
 if ($this->query_id) {
  $this->result = mysql_fetch_object($this->query_id);
  return $this->result;
 }
 }

// 获取 num_rows
 public function num_rows () {
 if ($this->query_id) {
  $this->num_rows = mysql_num_rows($this->query_id);
  return $this->num_rows;
 }
 }

// 获取 insert_id
 public function insert_id () {
 return $this->insert_id = mysql_insert_id();
 }

// 显示共有多少张表
 public function show_tables () {
 $this->query("show tables");
 if ($this->query_id) {
  echo "数据库 $this->db_name 共有 ".$this->num_rows($this->query_id)." 张表
";
  $i = 1;
  while ($row = $this->fetch_array($this->query_id)){
    echo "$i -- $row[0]
";
    $i ++;
  }
 }
 }

// 显示共有多少个数据库
 public function show_dbs(){
 $this->query("show databases");
 if ($this->query_id) {
  echo "共有数据库 ".$this->num_rows($this->query_id)." 个
";
  $i = 1;
  while ($this->row = $this->fetch_array($this->query_id)){
    echo "$i -- ".$this->row[database]."
";
    $i ++;
  }
 }
 }

// 删除数据库：返回删除结果
 public function drop_db ($db_name='') {
  if ($db_name == '') {
   $db_name = $this->db_name;//默认删除当前数据库
  $this->query("drop database $db_name");
 }else {
  $this->query("drop database $db_name");
 }
 if ($this->query_id) {
  return "数据库 $db_name 删除成功";
 }else {
  $this->show_error("数据库 $db_name 删除失败");
 }
}

// 删除数据表：返回删除结果
 public function drop_table ($table_name) {
 $this->query("drop table $table_name");
  if ($this->query_id) {
  return "数据表 $table_name 删除成功";
 }else {
  $this->show_error("数据表 $table_name 删除失败");
 }

}

// 创建数据库
public function create_db ($db_name) {
 $this->query("create database $db_name");
 if($this->query_id){
  return "数据库 $db_name 创建成功";
 }else {
  $this->show_error("数据库 $db_name 创建失败");
 }
}

// 获取数据库版本
 public function get_info(){
 echo mysql_get_server_info();
 }

// 显示错误信息
 public function show_error ($msg) {
 $errinfo = mysql_error();
 echo "错误：$msg
返回：$errinfo

";
 }

// 释放内存
 public function free_result () {
 if ( @mysql_free_result($this->query_id) )
 unset ($this->result);
 $this->query_id = 0;
 }

} // end class