php mysql 连接 数据库选择 显示所有表

这里主要是讲关于在php中数据库连接与数据库选择以及显示当前数据库所有表三个实用函数，有需要的朋友可以看看。

$phps教程ql_user = "root";
$phpsql_password = "root";
$phpsql_loc = "";
$phpsql_db = "";

function phpsql_connect($location, $username, $password){
 global $phpsql_loc, $phpsql_user, $phpsql_password;
 if($phpsql_user != $username || $phpsql_password != $password)
 phpsql_error("cannot access to phpsql!(wrong username/wrong password)");
 define(phpsql_loc, $location);
 $phpsql_loc = $location;
}
function phpsql_select_db($db){
 global $phpsql_db;
 define(phpsql_db, $db);
 $phpsql_db = $db;
}
function phpsql_list_table(){
 global $phpsql_loc, $phpsql_db;
 $i = 0;
 if(!($handle = @opendir($phpsql_loc."/".$phpsql_db)))
 return 0;
 while(($file = readdir($handle)) !== false){
  if($file != "." && $file != "..")
  {
  $table[$i ++] = $file;
  }
 }
 return $table;
}

php与mysql是黄金组合，现在我们来讲一下关于php查询mysql数据库记录实现，主要会用到函数mysql_connect mysql_query mysql_select_db mysql_fetch_array四个php函数，下面看实现。

$hostname="localhost";         //定义连接到的mysql服务器名
$username="root";          //定义用于连接的用户名
$password="";           //定义用于连接的密码
$link=mysql_connect($hostname,$username,$password);   //打开msql连接
mysql_query('set names gb2312;');      //转换编码以支持中文
mysql_select_db("test");         //选择操作库为test
$query="select * from friends";       //定义sql
$result=mysql_query($query);        //发送sql查询
while($rows=mysql_fetch_array($result))
{
  echo "id为：".$rows[id];
  echo "<br>www.111cn.netn";
  echo "name为：".$rows[name];
  echo "<br>n";
  echo "sex为：".$rows[sex];
  echo "<br>n";
  echo "birthday为：".$rows[birthday];
  echo "<br>n";
  echo "address为：".$rows[address];
  echo "<p>n";
}
//释放结果集
mysql_free_result($result);

//条件查询

$query="select * from friends where id=1";     //定义sql
$result= mysql_query($query);     //发送sql查询
echo mysql_result($result,0,"name");       //输出name结果
echo "<br>";
echo mysql_result($result,0,"birthday");      //输出birthday结果
echo "<br>";
echo mysql_result($result,0,"sex");       //输出sex结果
echo "<br>";
echo mysql_result($result,0,"address");      //输出address结果

//相关操作

$conn=mysql_connect('localhost','root','');       //打开连接
$fields=mysql_list_fields("test","friends",$conn);     //列出test库friends表的信息
$cols=mysql_num_fields($fields);        //获取结果数
for($i=0;$i<$cols;$i++)          //循环
{
  echo mysql_field_name($fields,$i)."n";       //输出字段名
  echo "<p>";
}

/*
总结

在php中查询数据库记录是相当简单且常用的，只要你记录上面几个函数就可以实现数据查询了。
*/

这里提供的数据库连接类程序，后面还提供了一个sql安全检测函数与sql语句完整性检测函数。*/

class db_mysql {
 var $connid;
 var $querynum = 0;
 var $expires;
 var $cursor = 0;
 var $cache_id = '';
 var $cache_file = '';
 var $cache_expires = '';
 var $halt = 0;
 var $result = array();

 function connect($dbhost, $dbuser, $dbpw, $dbname, $pconnect = 0) {
  global $cfg;
  $this->expires = $cfg['db_expires'];
  $func = $pconnect == 1 ? 'mysql_pconnect' : 'mysql_connect';
  if(!$this->connid = $func($dbhost, $dbuser, $dbpw)) {
   $this->halt('can not connect to mysql server');
  }
  if($this->version() > '4.1' && $cfg['db_charset']) {
   mysql_query("set names '".$cfg['db_charset']."'" , $this->connid);
  }
  if($this->version() > '5.0') {
   mysql_query("set sql_mode=''" , $this->connid);
  }
  if($dbname) {
   if(!mysql_select_db($dbname , $this->connid)) {
    $this->halt('cannot use database '.$dbname);
   }
  }
  return $this->connid;
 }

 function select_db($dbname) {
  return mysql_select_db($dbname , $this->connid);
 }

 function query($sql , $type = '', $expires = 0, $save_id = false) {
        $sql=checksql($sql);
  if($type == 'cache' && stristr($sql, 'select')) {
   $this->cursor = 0;
   $this->cache_id = md5($sql);
   $this->result = array();
   $this->cache_expires = $expires ? $expires + mt_rand(-9, 9) : $this->expires;
   return $this->_query($sql);
  }
  if(!$save_id) $this->cache_id = 0;
  $func = $type == 'unbuffered' ? 'mysql_unbuffered_query' : 'mysql_query';
  if(!($query = $func($sql , $this->connid)) && $this->halt) {
   $this->halt('mysql query error', $sql);
  }
  $this->querynum++;
  return $query;
 }

 function get_one($sql, $type = '', $expires = 0) {
  $query = $this->query($sql, $type, $expires);
  $r = $this->fetch_array($query);
  $this->free_result($query);
  return $r ;
 }
 
 function counter($table, $condition = '', $type = '', $expires = 0) {
  global $cfg;
  $table = strpos($table, $cfg['tb_pre']) === false ? $cfg['tb_pre'].$table : $table;
  $sql = "select count(*) as num from {$table}";
  if($condition) $sql .= " where $condition";
  $r = $this->get_one($sql, $type, $expires);
  return $r ? $r['num'] : 0;
 }

 function fetch_array($query, $result_type = mysql_assoc) {
  return $this->cache_id ? $this->_fetch_array($query) : @mysql_fetch_array($query, $result_type);
 }

 function affected_rows() {
  return mysql_affected_rows($this->connid);
 }

 function num_rows($query) {
  return mysql_num_rows($query);
 }

 function num_fields($query) {
  return mysql_num_fields($query);
 }
 function escape_string($str){
  return mysql_escape_string($str);
 }
 function result($query, $row) {
  return @mysql_result($query, $row);
 }

 function free_result($query) {
  return @mysql_free_result($query);
 }

 function insert_id() {
  return mysql_insert_id($this->connid);
 }

 function fetch_row($query) {
  return mysql_fetch_row($query);
 }

 function version() {
  return mysql_get_server_info($this->connid);
 }

 function close() {
  return mysql_close($this->connid);
 }

 function error() {
  return @mysql_error($this->connid);
 }

 function errno() {
  return intval(@mysql_errno($this->connid)) ;
 }

 function halt($message = '', $sql = '') {
  global $cfg;
  if($message) {
   if($cfg['errlog']) {
    $log = "query:$sql|errno:".$this->errno()."|error:".$this->error()."|errmsg:$message";
    log_write($log, 'sql');
   }
  }
        showmsg("mysqlerror:$message",'-1');
        exit();
 }

 function _query($sql) {
  global $fr_time;
  $this->cache_file = cache_root.'/sql/'.substr($this->cache_id, 0, 2).'/'.$this->cache_id.'.php教程';
  if(!is_file($this->cache_file) || ($fr_time - @filemtime($this->cache_file) > $this->cache_expires)) {
   $tmp = array();
   $result = $this->query($sql, '', '', true);
   while($r = mysql_fetch_array($result, mysql_assoc)) {
    $tmp[] = $r;
   }
   $this->result = $tmp;
   $this->free_result($result);
   file_put($this->cache_file, "<?php /*".( $fr_time+$this->cache_expires)."*/ return ".var_export($this->result, true).";n?>");
  } else {
      $this->result = include $this->cache_file;
  }
  return $this->result;
 }

 function _fetch_array($query = array()) {
  if($query) $this->result = $query;
  if(isset($this->result[$this->cursor])) {
   return $this->result[$this->cursor++];
  } else {
   $this->cursor = $this->cache_id = 0;
   return array();
  }
 }
}

function checksql($dbstr,$querytype='select'){
 $clean = '';
 $old_pos = 0;
 $pos = -1;
 //普通语句，直接过滤特殊语法
 if($querytype=='select'){
  $nastr = "/[^0-9a-z@._-]{1,}(union|sleep|benchmark|load_file|outfile)[^0-9a-z@.-]{1,}/i";
  if(preg_match($nastr,$dbstr)){
            log_write($dbstr,'sql');
            showmsg('safeerror:10001', '网页特效:;');
            exit();
  }
 }
 //完整的sql检查
 while (true){
  $pos = strpos($dbstr, ''', $pos + 1);
  if ($pos === false){
   break;
  }
  $clean .= substr($dbstr, $old_pos, $pos - $old_pos);
  while (true){
   $pos1 = strpos($dbstr, ''', $pos + 1);
   $pos2 = strpos($dbstr, '', $pos + 1);
   if ($pos1 === false){
    break;
   }
   elseif ($pos2 == false || $pos2 > $pos1){
    $pos = $pos1;
    break;
   }
   $pos = $pos2 + 1;
  }
  $clean .= '$s$';
  $old_pos = $pos + 1;
 }
 $clean .= substr($dbstr, $old_pos);
 $clean = trim(strtolower(preg_replace(array('~s+~s' ), array(' '), $clean)));
 if (strpos($clean, 'union') !== false && preg_match('~(^|[^a-z])union($|[^[a-z])~s', $clean) != 0){
  $fail = true;
 }
 elseif (strpos($clean, '/*') > 2 || strpos($clean, '--') !== false || strpos($clean, '#') !== false){
  $fail = true;
 }
 elseif (strpos($clean, 'sleep') !== false && preg_match('~(^|[^a-z])sleep($|[^[a-z])~s', $clean) != 0){
  $fail = true;
 }
 elseif (strpos($clean, 'benchmark') !== false && preg_match('~(^|[^a-z])benchmark($|[^[a-z])~s', $clean) != 0){
  $fail = true;
 }
 elseif (strpos($clean, 'load_file') !== false && preg_match('~(^|[^a-z])load_file($|[^[a-z])~s', $clean) != 0){
  $fail = true;
 }
 elseif (strpos($clean, 'into outfile') !== false && preg_match('~(^|[^a-z])intos+outfile($|[^[a-z])~s', $clean) != 0){
  $fail = true;
 }
 elseif (preg_match('~([^)]*?select~s', $clean) != 0){
  $fail = true;
 }
 if (!empty($fail)){
        log_write($dbstr,'sql');
        showmsg('safeerror:10002', 'javascript:;');exit;
 }
 else
 {
  return $dbstr;
 }
}

下面只告诉你如何实现图片如何保存到数据库教程，不推荐此种方法。
*/

mysql_connect('localhost','root','root');
mysql_select_db('ac');
$picdir ="/a/ag.gif";
$image = addslashes(file_get_contents($picdir));
$sql ="insert into tbl_name (field) values ('" . $image . "')";
mysql_query($sql);

/*
--
-- 表的结构 `test`
--

create table if not exists `test` (
  `id` int(8) not null auto_increment,
  `title` char(150) default null,
  `content` longblob,
  `addnewcolumn` varchar(20) not null,
  primary key  (`id`)
) engine=myisam default charset=utf8 auto_increment=1 ;

<html>
<head>
<title></title>
</head>
<body>
<?php
$mysql_server_name='localhost';
$mysql_username='root';
$mysql_password='000000';
$mysql_database='lib';
$conn=mysql_connect($mysql_server_name,$mysql_username,$mysql_password,$mysql_database);
$sql="select name,age from mytb";
print($conn);
$rs=mysql_db_query("lib","select * from mytb",$conn);
print("
<br>");
while($row = mysql_fetch_object($rs)){
print ($row->name.":".$row->age."<br>");
}
mysql_close($conn);
?>

　　

显示如下：

resource id #1

dd:54
ddd:8
??:15
???:25
??:32

　　mysql编码：utf8,gbk都试过了。mysql font 和命令行显示都正确。

　　问题补充：

　　乱码:

???:15
???:25
??:32

　　这几行,数据库教程里的值是汉字.显示出来的是问号.

　　解决办法：

　

　在$rs=mysql_db_query("lib","select * from mytb",$conn);

　　前面加上

　　

mysql_query("set names gb2312");或者mysql_query("set names gbk");

下面看一下关于解决乱码的方法

.gb2312,gbk,utf8等支持多字节编码的字符集都可以储存汉字，gb2312中的汉字数量远少于gbk，而gb2312,gbk等都可在utf8下编码。

　　二.用命令show variables like 'character_set_%';查看当前字符集设定：

mysql> show variables like 'character_set_%';
+--------------------------+--------+
| variable_name　　　　　　| value　|
+--------------------------+--------+
| character_set_client　　 | gb2312 |
| character_set_connection | gb2312 |
| character_set_database　 | gb2312 |
| character_set_filesystem | binary |
| character_set_results　　| gb2312 |
| character_set_server　　 | latin1 |
| character_set_system　　 | utf8　 |
+--------------------------+--------+
7 rows in set (0.02 sec)

　　

(这里设置的字符是gb2312)

　　显示中文乱码主要有两个设置:character_set_connection 和character_set_results ,

　　如果你的这两个设置不支持中文编码,就会出现乱码,只要:set character_set_results =gbk;就设置中文编码了。

　　三.set names charset_name;可以一次性设置客户端的所有字符集。