php查询mysql数据表记录实现代码

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。
*/

在php中连接mysql数据库有二种如有mysql_connect 与mysql_pconnect，一个是软连接，一个是持续连接，两者区别在于一个当页面浏览完自动关闭已经打开的MySQL连接页mysql_pconnect如果不关闭就一直连接。

$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);  //连接到本地mysql服务器
if($link)           //如果成功连接
{
  echo "成功连接";         //输出内容
}
else            //如果连接失败
{
  echo "连接失败";         //输出内容
}
//mysql_close($link) //关闭已经打开的mysql连接

//mysql_pconnect连接mysql数据库

$link=mysql_pconnect($hostname,$username,$password);  //打开持续性连接
if(!$link)            //如果不能连接
{
  die('不能连接'.mysql_error());        //输出信息
  exit();            //结束所有php操作
}
echo '持续连接成功';

/*
下面看软连接查询数据库内容

*/

$link=mysql_connect($hostname,$username,$password)or die("could not connect:".mysql_error());
//转换编码以支持中文
mysql_query('set   names   gb2312;');
//选择操作库test
mysql_select_db("test")or die("could not select database:".mysql_error());
//执行sql查询，从表中选择名字
$query="select name from friends";
$result=mysql_query($query)or die("query failed:".mysql_error());
//匹配结果集到行循环输出内容
for($i=mysql_num_rows($result)-1;$i>=0;$i--)
{
//移动内部结果的指针，如果没有结果则输内容
  if(!mysql_data_seek($result,$i))
  {
    echo "cannot seek to row $i:".mysql_error()."n";
    continue;
  }
//从查询结果取得一行作为对象
  if(!($row=mysql_fetch_object($result)))
  continue;
//输出结果内容
  echo "$row->name<br/>n";
}
//释放结果集
mysql_free_result($result);

/*
其它操作

$escaped_item=mysql_escape_string($str);    //将字符串转义
printf("escaped string:%sn",$escaped_item);    //输出转义后的结果

$mydb=mysql_list_dbs($link);      //列出数据库
while($result=mysql_fetch_object($mydb))   //通过循环遍历结果集并赋值给对象
{
  echo $result->database."n";      //输出对象内容
  echo "<br>";
}

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;
}

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 ;